One of the points that came up from the #mastodonmeetup in Helsinki: there is a precedent for the kind of shift we are seeing from #Twitter to #Mastodon. When #Freenode #IRC went all bananas, people and projects started leaving in droves. Freenode is now completely empty.
Now the scale is different, of course, but it shows what can happen.
We are witnessing the biggest platform transition of our time. I'm still not sure if it's sustainable (it really depends on how #Mastodon can eat up the different people coming), but as a phenomenon it is incredible.
@Setok freenode users migrated to libera.chat IRC and Matrix. Freenode episode demonstrated how IRC is centralized (to networks) and not fully controlled by it's users.
I predict in long term the decentalized alterntives will win.
@cos the point was that there has been one case of a well known platform being emptied of its users due to policies. It's much less likely to happen to #Twitter, but it could.
On centralisation you could argue #Mastodon instances are centralised too — especially the big ones. Of course being able to switch your account helps, and at least they are interlinked (unless blocking gets out of hand).