The triple whammy of bonus stats, true damage, and healing that doesn't reduce from aoe is actually worse than when it had double the true damage. Tanks don't get to win in lane, and thus can't come out ahead to coast into the mid and late game. Instead, they either get crushed in lane or get crushed after the enemy fighter/skirmisher completes an item or so. Sure, they're useful for team fight cc, but what's the point when you feed a carry while you're trying to get to the team fighting stages of the game?
ALL tanks aren't useless. Support tanks and jg tanks are still a thing, but top lane tanks? They haven't been relevant to the game for a minute, even longer if you exclude Sion. Maybe Riot should focus less on fighters and marksmen and assassins all the time and put a little elbow grease in their lesser loved sub-classes for a change? After 7 years before finally having SOMEONE touch the enchanter class (a newbie, no less), why the hell is it that some roles/niches gather cobwebs and other ones just CONSTANTLY get worked on? What's the deal?
I don't even want to say anything about artillery mages and how THEY are in this game rn.