Ah, I see, I thought you were talking about technical difficulties or instances being hard to find, but you rather meant habits or mindsets making it hard. I really get that.
But then it's cool that so many people still decided to join the fediverse, which is, after all, a way smaller network than the big corporate platforms. 😃 Maybe this habit of going for big numbers changes when people get used to the fediverse.

I also get the FOMO due to defederation thing, it definitely makes sense. But imho spreading out over several more instances could even help here.
Defederating will always exist, but if there are a lot of small instances and one of them decides to block another one, people on this instance would only lose contact to a fraction of the total content of the fediverse.
However, if there are only a few big instances and one decides to block another, people would get seperated from a whole lot of content.

I do see the issue, however, that if you are interested in some specific communities that are on a specific instance and yours, for whatever reason, decides to defederate just from this one, you would lose contact to exactly those communities you follow.
At least I think that's the way it is. It could also be that you could still follow the communities from a blocked insance and still post and see the majority of posts in it, but you just don't see posts and comments from users of the blocked instance. I really don't know.
Either way, Lemmy and kbin are both in early developement stage and if this issue exists there might be a solution for this in the future. 😃
And let's say the problem does exist and you don't want to stay on an instance that's blocking your favourite community, I think emotionally it's easier to move from one small instance to another small one than it is to move from a big to a small one. 😊