What @jerry suggests here, or elsewhere in the tread, or what I infer from the comments across the thread, is a combination of social and technical measures, and they're not so different from what @mekkaokereke suggests:
- The onboarding experience is key. People come in from JoinMastodon, and need to be presented with good information with which to make good choices.
- Servers you can easily reach from JoinMastodon need to have at least a basic level of blocking of the vilest troll instances. Good defaults.
- Server admins and/or members need to be able to subscribe to collaboratively managed blocklists. Good tool support for good social mechanisms.
Okereke's pinned post, which asks for a superset of a subset of what I just said: