I used TikTok and also never came across a meme like that. Or maybe I did once or twice, I just quickly swiped away (or if something I’m not interested in is shown repeatedly I click not interested and it’s gone at least for a long time). If you’re shown the same meme from 20 different people chances are you just kept watching them, maybe with disapproval, but your device can’t read your brainwaves yet so the service just thinks you’re super interested.

And YouTube also had those stupid challenges with everyone doing the same stupid shit before TikTok even existed.

It’s a culture thing I guess. Overlay videos of other videos and the memeing videos has been in TikTok since the beginning. Youtube would probably ban the former under a copyright strike or something.