“Mastodon” is a program. It has absolutely no agency whatsoever, and without agency there is no responsibility.
So now you’re probably really saying “Mastodon’s developers” have responsibility.
Good. Pay them. Writing software is a huge job, and getting your software suddenly stress-tested by millions of users abandoning a sinking ship is a good way to get overloaded and even burned out. So you think they have responsibility for something? Help them get it done. Beginning with paying their foundation so that they can hire more people to do it.
Coming in and writing a huge rambling set of demands is not how you’re going to get anything changed.