Because teenagers will always want to rebel against the status quo. It's one of those "nobody goes there anymore because it's always too crowded" situations. It's no longer cool to listen to that band because they're on the radio now and everyone listens. It's no longer cool to post on that site because everyone's mom is there now. etc etc etc.

At some point, moms will once again infiltrate TikTok to make the kids not want to be there. Something else will pop up in its place, and the process will start all over. again.