I was wondering the same thing. Do some people in the comments here really think it's bad that fediverse instances are highly connected? Because actually, having more disconnected servers leads to more centralization. That's the whole point of federation. With federation, small sites that otherwise wouldn't have enough content to keep people interested can draw content from other sites, giving people more reason to stay. So it is imperative to have highly connected servers for decentralization to succeed.
I see instance memberships like passports. You could have multiple, but you ideally want just your home one for simplicity. Some passports are stronger than others because they let you travel to more places more conveniently, e.g. Japan and USA. So following this metaphor, lemmy.ml is the strongest passport. It federates with practically every other lemmy instance except a couple on the blocklist. Compare this to other instances that federate with only a couple instances. Who would want to join those? It would be like wanting to repatriate to Syria.
This was my experience when I made my account. I wanted to avoid lemmy.ml because I believe in distributing lemmy users across instances. But at the time all of the instances had so much weaker access in comparison. I couldn't bring myself to do it. So I joined lemmy.ml like a lot of other people did. And the state of the lemmy network now is that 15k users are on lemmy.ml, and the other instances are in the dozens on average. I have ideas on how this can be addressed, but I think I've rambled enough for now.