Not to forget the TwitterAPIpocalypse of 2012 (?), when Twitter heavily restricted its programming interfaces, which decimated the ecology of companies that were built around it, like Flattr (1.0). I surmise that's not unrelated to Mastodon's release in 2016 ?

For instance :

IFTTT forced to remove Twitter triggers to comply with new API policies :

https://news.ycombinator.com/item?id=4550625