The title undersells the magnitude of the change a bit in my opinion. By default, mastodon now encourages new users to sign-up on https://mastodon.social which has caused a bit of a kerfuffle in the fediverse.

Personally, I'm largely ambivalent to the change; I understand the reasoning, and it's what https://element.io has been doing for https://matrix.org since the beginning. It is more than a bit of a sea-change though given the fediverse's prevailing culture.