@FediThing It does create more friction in signing up, especially for people who have no existing connections in or familiarity with the fedi culture, because it's often not clear what to expect from an approval process (do you need to have a good reason? is it just a spot check? etc.) and it can feel like a job application or something fragile, as if you could get thrown out at any moment.
I don't think these are necessarily good reasons to not have an approval process, and I think a lot of improvements are possible there to mitigate these issues (including eg. invite systems), but this does seem to be something a fair amount of people run into (undoubtedly due to cultural expectations built up by big tech platforms).