My bad, I've edited the post to better reflect that point.
As for the problem I'm trying to address and how this would help, as I and others have said in here, trying to find games that are trying to be commercially viable and entertaining vs games that are explicitly non-commercial and experimental is difficult. Yes I could use the artgames tag but 1) it's a vague enough term that many games that are non-commercial don't fit into it, or are on the blurry edges, and 2) it's not prominently displayed anywhere - you'd effectively need to know about it to use it, and 3) You can't negate tags in the itch search, so you can't filter out the games that do know about the tag and have decided they fit in that category if you're looking for commercial games.
By making the tags prominent and official, it makes it significantly easier for a newcomer to find a jumping off point and funnel down to the games they actually want, instead of meeting resistance when they just want a fun FPS and have to wade through a ton of 7DFPS jam games, and vice versa.