I've never used Tumblr much less its alternatives, but on the Threadiverse side, before PieFed solved the onboarding problem (and I hear that upcoming Lemmy v1.0 may improve things for it too?), it required quite a bit of effort to be the first person on an instance to sign up to a community. For one thing you already had to know the precise name for it, having looked it up elsewhere, and even after the Rexodus often you couldn't even use the community lookup tools to kickstart that and had to resort to direct URL manipulation. (Edit: oh, and the community name most often was not the same as the name displayed for it, with some methods like 3rd-party apps usually not showing the actual name very readily.) And for another thing it can be quite unintuitive to people when signing up does not appear to work right away but instead over the course of several days to like a week the posts start appearing - except not older posts but only newer ones (and not all new ones, but only some, especially when defederations are involved). Therefore I tried to help by signing up for communities whenever I could to help get the smaller instances I was on a head-start, even if I had no interest in them and left them later, just to make it easier for future people to simply click the subscribe button (and even that causes confusion, when some older content is present but then not all of it).
Anyway, the entire Fediverse is newer and the tools often are not so easy to use. It is like using a Linux CLI: quite worthwhile to learn and powerful after you do, even though it requires a rather large investment into learning how. Normally for someone not tech oriented I would strongly suggest to join one of the medium to larger-sized instances (while avoiding the absolute largest of course, to more evenly distribute the load), so that someone else has done the largest majority of this effort, and they can simply enjoy the content and contribute in other ways - voting, commenting, and posting - without being distracted by the underlying technical procedures of how it all works underneath the hood.
This is not an objective fact but an opinion (whether well-substantiated or not I cannot tell). I am not clicking on a Facebook link to learn more, so thank you for adding some additional context here.
There is also a !yepowertrippinbastards@lemmy.dbzer0.com community that will certainly agree with you that anything done by a .world community moderator is by definition wrong.
As for myself I have no opinion on this currently, but only questions like banning one person does not make a place authoritarian/fascist but a pattern of such events would. All that this post says though is a complaint about the one person - again, whether justified or not I have no idea, as other commenters here are likewise saying, we simply do not currently have the facts to be able to judge properly.