I feel like letting this go would be agreeing that it's mediocre, so I approved it. I'm no art student nor an expert in the field, but I think most would agree it's a fine looking portrait, right? Plus, this artist, though not Japanese, works in Japan and does draw anime style drawings so...
Except one is a digital art piece about current days pop culture by a popular artist while the other is a classical piece that has nothing to do with current days pop culture.
That's one distinction, yes, and I could very well bring up contemporary examples to compare this to. I don't see what modern pop culture has to do with anything, unless it's modern anime pop culture, which this post is not. Michelangelo's David also has nothing to do with it, hence why the comparison works. Both have nothing to do with anime, however the one that's universally known as one of the greatest artworks to come out of that little art movement from Florence let alone all of human history is not the one currently active.
Ilya was a fine artist and all, but what put him on the map and what people look for on this site are his anime themed pieces. If this post were not by Ilya but rather a new Tumblr account that you stumbled upon would you post it? The case to upload it would be without merit because the argument is that artists who generally post anime should have their occasional western-exclusive pieces accepted too which does not stand to reason. We should asses every image singularly, on it's own merits, not ascribe it value just because of the artist...
Not every single traced portrait Ilya puts out deserves to be posted. And while I acquiesce for his normal fare as of late (really it used to be much better), this piece is wholly removed from any criterion for what is on topic.
Japanese-origin video games are considered part of "anime culture" in Danbooru, which just gets shortened into "anime". Games like Touhou have always been on-topic for Danbooru, as was Kantai Collection before it got an anime, and those obviously make up an overwhelming bulk of Danbooru's content. Trying to argue against Danbooru's anime focus by arguing about Japanese games is kind of missing the point.
Beyond that, I'll say again what I said in the forum: I don't see why being from an artist that has drawn much better quality work somehow means we shouldn't judge the quality of each individual piece on its own merits. (Nor does "it's that artist's style to draw like this" an excuse for a shitty art style, while I'm on the topic...) Some of these Kuvshinov works are literally cell phone pictures of doodles. Leonardo da Vinci did plenty of doodles on scrap paper too, but they don't all get put on display at the Louvre.