How did you escape your locker, Davy? (ba-dum-bump)

I don’t know much about the software side, but I’d venture that (as with some instances) not all of them are necessarily trying to put much energy in to growing their userbases. That is, some might be set up to meet the needs of a smallish group, and might not be particularly interested in outsiders joining. That’s just speculation though, purely extrapolated from the fact that some have set up their instances across the “FV” for that kind of purpose.

In other cases, I take it that such services are only federating to a limited portion of the FV, and that may indeed be a problem worth fixing sooner rather than later. For example, the four biggest user-bases by software (M, misskey, nodeBB and sharkey) don’t seem to federate well, or at all, to the ‘Lemmy’ side of the FV. At least IME, and in terms of the network I’m on (PieFed).