That's because DA doesn't have any moderation. You can upload any old crap there
Everything here has to pass through moderation. It saves the public from rips, items which don't work, items likely to cause offence and anything else not fit to be let loose.
DeviantArt is a free-for-all, for all sorts of art and is of a size that it's impractical to do submission moderation. Trust me when I say that moderation does wonders for our available gallery. We weed out broken submissions, inappropriate ones, miscategorized ones, and in some cases truely aweful ones (I'm talking MS Paint works).
We're not going to go to an open submission system. Simply is not going to happen.
I love deviantART.
However, their system wouldn't work so well here because our content is mostly focused around software that takes that content and applies it to a program or the entire system. If someone uploads something that's broken or whatever, it's not just a minor annoyance to the user.