hot take maybe: but alot of these shifts have come with the sheer explosion in number of people on these platforms and online in general - the arrival of many/most of the mainstream/normies as it were. Perhaps the reality is that alot of these people's lives on and offline actually are dominated by 'fads' and so this is just naturally following that.

Think 'keeping up with the jones', 'the latest fahsion, food, entertainment, music, x, trends' etc. People live by what I dunno, magazines, Oprah, local morning show hosts, entertainment news shows, etc, tell them. They've brought that view of things with them online.