I am writing this journal for the 3d artist that have questioned the lack of any 3d art chosen in the "Tomb Raider Reborn" Contest.
These are my own opinions after much research and investigation.
First and most importantly is the Legal aspect of "3d pre-made models". The argument can be made that everything that you may have used to create a Render you also have an EULA (End User License Agreement). DAZ Studio EULA can be found here. www.daz3d.com/eula
However there are many many different url's where you can find other models that can be used in your render, and each will have its own EULA. Keeping up with all the EULA's that may be found in your render causes 3d art to become problematic for a commercial company to use.
You may create a render in 3d and even sell that render to a customer that loves it, However if there becomes a legal altercation, the burden of proof of your legal use of said model is on the artist,
In the Case of deviantART or any 3rd party company involved in the contest may not wish to simply take your word that you have all the Eula's, nor do they wish to investigate that each 3d entry into the contest has every EULA to make that entry legal. Nether do they wish to set themselves up to have to be responsible for any burden of proof at all. Basically deviantArt is not saying your 3d Entry is illegal, they just don't want the burden of proof on themselves or the work necessary to make sure it is legal. The Man Hours required to constantly investigate every 3d render would be significant. I am sure that deviantART would have to raise the price of every account to cover that cost.
deviantART does not wish to be viewed as Biased towards any medium. Therefore they are not going to say that any medium is not allowed to enter the contest. However they do retain the right to judge your entry as applicable or not for a Said Contest.
I would like to repeat that these are my opinions and I am not in myself deviantART nether do I represent deviantART or claim that these are deviantARTs opinions or rules.
They are only my opinions that I have come to after my exhaustive investigation.
I hope this helps other 3d artists to answer any questions they may have.