I'm starting to think that the right use-case for Mastodon is not as a Twitter alternative (long-term public presence) but as a Slack alternative (private and often short-lived discussion groups, or organizational intranet).

A group is motivated to pay for its own instance so long as it is useful... Who is motivated to operate one as a public service, with years-long commitment?

For all users, it's worth checking out the mastodon.social content moderation guidelines, at https://mastodon.social/about/more

As @sonya points out, not everyone may be happy with them.

As our host @Gargron point out, if you don't like them, you can run your own instance.

But instances choose who they peer with... so the Mastodon-based network may balkanize.

The Right Thing is a model in which everyone runs their own server and has total control over their identity and their data. "Running a server" should, and could, require no technical knowledge. It would run on the cloud service of your choice (AWS e.g.) and you would pay them a few $$ per month for that. Transparently move to a different one if you don't like them.

It looks like you can export your data from an instance, but there doesn't seem to be actual identity portability.

This means that users have to choose a provider carefully, to trust that they are going to be in operation for the long haul.

That means evaluating their business model to figure out if they are going to have the money to pay for enough servers to eliminate the 500 Internal Server Errors!