First, regarding competitions in general - they are simply not for everyone. That is not to say that only certain individuals should enter, but rather that they have a certain focus and certain requirements. They have rules. Typically, you would find out the specific rules in advance and make sure that your item, and the requisite documentation, are suitable for the specific competition. When you enter your item/s you are acknowledging that set of rules, or that a certain set of criteria will be used to judge them. You might enter knowing that facet of your entry might not stand as strong as the rest, but there is nothing wrong with that. Typically you will get good feedback from the judges that will help you strengthen that portion of the entry for a later event.
Quite often that area that falls short is the documentation. Now, there is a constant stream of "documentation hate" on forums, but it really does serve a purpose. The documentation firstly serves to educate a judge. If they do not know a great deal about your entry, it can help them to see the back ground of the item and the sources you used. The documentation also serves to show your process. How did you personally go about making this item? (And ideally, how did your process or materials differ than those in period?) The real value in this part of your documentation is really for those who visit the display, as well as the judges. Seeing how your crafted your item can inspire someone else to try your craft. Or it might give them a solution on how to overcome an obstacle in their own work.
I know that some Kingdoms limit documentation length, while in others the more thorough you are, the better.
Now, my opinion is that if you have two entries that are otherwise equal, and one has EZ documentation and the other a longer, very thorough written piece describing the process in detail, then the latter should absolutely win. It is no different than having two identical garments, with one being hand sewn and the other sewn on a machine. They are both lovely, both have good sources, both are tailored well, but one simply had more effort involved in one portion of the process.
This does not mean that there is anything wrong with either machine sewing or using EZ doc! Not every aspect of every competition is suited to every individual. The person who excels at all parts of it should indeed be the winner. It is no different than a heavy tournament that requires that you fight a different weapon style each round. Anyone could enter, but if someone has only gained mastery over sword and board, they will likely not go far in the tournament. It does not mean that they cannot enter, or enjoy themselves, or learn something from the whole experience, it just means that they are not likely to win (and they know that going onto the field).
If your major issue with competitions is the written documentation, there are often many who would be willing to help work you through it and at least assemble a decent sheet of simple documentation. Adding in clear photos of your process (as well as sources) can help the judges as well. Some Kingdoms have competitions with in-person judging. Those can be of great benefit to excellent artisans who do not have well written documentation, but who do have an excellent knowledge of resources. (Note that you should have a good understanding of your resources when competing, even if you do not have a lengthy written documentation sheet.)
It is also important to remember that competing is not, and should not, be the only expression of the arts in the SCA. There are many ways to share your art that go beyond competing. Open displays are fantastic venues, especially if you can sit with your entry and talk about your work to others. Teaching is often the most valuable way to share your work, your research, and your skills. I know that some artisans feel pressured to compete, but you should not. If you really dislike the idea of competitions (and as I mentioned before, they are nor for everyone), find other ways to get out there, share what you do and inspire others.
On Art & Science
I think that when we start out as artisans in the SCA we are actually, despite our chosen craft, all scientists. There is little room for original art when still learning the very basics of the trade. We practice the simplest steps over and over, working out details as we go. Eventually, we start adding in additional elements, additional knowledge and additional steps until we are producing art.
Recently I have seen two people lamenting that in their area only reproduction pieces can win a competition. I can happily say that that is not the case in the areas in which I play. I have personally had items win that were experimental archaeology and one that, in fact, has no extant item at all on which it could be based. Rather it is conjecture of how scraps of evidence go together. I really feel that there is room (or should be room) in competitions for a variety of projects, but I find it very important to note here that stepping away from extant items will usually mean that you need exceptionally strong documentation to back up your choices for every step of your work.
In fact, I do not think that reproducing an extant item is the height of artistry in the SCA. Mastery, to me, is when you understand not only the process of an art form, and have acquired the skill to execute it well, but when you have a deeper knowledge of the world surrounding the artisans of your chosen period and can try to look at the world through their eyes and create an original work of art that could indeed have existed in period. THAT to me is excellence.
Examples of this are SCA scrolls that are not copies of extant pieces, but that are made in the style of those those pieces but incorporate SCA elements into them or a tapestry in the Bayeux style that depicts a scene from an SCA tournament or a gown that could have been worn by a working class woman from Germany that is based on styles represented in period art from very specific times and locations and using archaeological data or records to support the fabric choices for the dress.
Those examples, to me, show not only that one has acquired the skills to craft something well, but that one has the foundation to go about creating original ART that reflects a period in time.
The key though, is that knowledge base. Being able to make logical connections between items and practices allows you to better understand things from the period artists point of view (and being able to know that if there is evidence from a 50 year period around your item, that that would be likely be a better resource than those dated over 100 years away). Your documentation is very key here because you need to let those judging your work know your thought process as to how the garments in a woodcut relate to those in a painting and how that relates to wills and records of textiles of a period and how all of the above influenced your choices in your original materials and process. It lets them see through your knowledge of a time and place and understand if, indeed, your work of art fits into that environment.
Personally, my favorite entries are usually those that are, in fact, original works of art. I love to see how someone works with the evidence to reach that understanding and craft something that is, for lack of a better term, transporting.