Exactly, the easy access and low barrier of entry (like reddit, twitter, etc.) make it perfect to populate. That's kind of why some of the instances need signups right, to keep out the riff riff?
Correct me if I am wrong but I think the lemmy Devs run the .ml instance and they have specifically said the do not want to be in control of a large general instance as they have enough on there plate just refining the code base.
Lemmy.world is I believe run by someone with a track record running a successful masterdon server so it looks well placed for growth atm
You probably can, but only if you have a good reason to want to be there specifically. (I'm posting this as my @lemmy.world account, but I also have a @lemmy.ml account that I asked for because I want to be involved with meta discussion about Lemmy and Lemmy development itself.)