It already is, and I know for certain that f:Smalldom was already tagged before your comment was posted because I tagged it around an hour or so after this went up.
Kek, sorry if it came across that way, acting like it wasn't there would have been BS, but to be fair, even if you knew what to look for, its easy to overlook tags in a big pile of them like this.
In the future I'd recommend taking tag suggestions here https://forums.e-hentai.org/index.php?showforum=89 Some things that should have a tag don't get one for specific reasons, but others its really just a matter of making the suggestion to get the ball rolling. Smalldom was added earlier this year after suggestion for another tag (smalltop, which was similar but did not require the small character to be dominant) derailed into adding smalldom instead.
@Glovelove You are a robot who don’t even understand nudity only purpose https://forums.e-hentai.org/index.php?showtopic=107861&st=10740 , I thought when forum-dweller/mod answer people question with non-answer, it was just mods telling ‘peasant’ user to read but no. Here we can see 2 forum elitists do it to each other, 3 replies from each and none get closer to figure out what does nudity only tag mean. no wonder you downvote comment that straightforwardly debunk the misuse of word “simp”, you have complex for overcomplicating thing and fear anything that explain it directly.