• Some people said that HTML5 games and other content are not "art". But I disagree. I come from the game design field and games are just as much art as the other fields of design or film (both of which are categories on here). And even if the game or animation is made purely for entertainment rather than for artistic purposes, that still doesn't dismiss the artistic merit of the work. On top of that, clearly deviantART acknowledges this... otherwise there would be no Flash category here because it's more or less the same sort of works.
The only other reason that I can imagine for not allowing such submissions is that it would take a lot of work implementing such a feature / making the site compatible with these deviations. And HTML5 is still relatively new, but since it is becoming a lot more widespread, I still think deviantART should consider it.