Ended up finding this explanation on WikiHow about how to choose a Mastodon server. "You can't really pick the wrong server on Mastodon" seems to me not great advice.
Was specifically thinking of this after seeing a new account that seems to be aimed at reaching a lot of people joining an instance that I know is at least limited by a lot of other instances. But that at first glance from the name and stated purpose would seem to fit the aims and subjects of that account.
It must be very hit and miss for people and groups coming in to the Fediverse without knowing the detailed histories to know which instances are federated with which. Those people then of course suffer lack of visibility and connection without actually having anything to do with for example poor moderation decisions of their instance (or even being aware of them).
Are there strategies for dealing with this? Would be interested on others perspectives on this, I assume it must be an issue that many people encounter.