Just to clarify, do you mean that whenever you post an image, it is automatically collected in a tab on an user's profile?
My two cents is that that is nigh impossible, as there would have to be an algorithm to check every post to see if it contained an image (including profile posts). And even if that existed, it wouldn't be able to discriminate between art, sprites, reaction gifs or just screenshots, so your gallery could end up showcasing other people's work as yours, or just 'non-art'. My personal opinion is that an art thread is a much more simple and accurate way to showcase your stuff, nor does it require a lot of effort to keep it going.
It's a nice idea, but I highly doubt it could be executed. Still, I'm not an admin, so it's not my call to make.