The analysis paralysis of having to pick an instance is definitely the biggest hurdle in my opinion. I don’t think a read-only instance is the solution though, at least not one that requires registration. That just adds another step, which I think would further confuse people. The simplest way to onboard new people is to just shove them onto the biggest instance, but I know that kind of goes against the ideology and creed of the fediverse. There were endless debates about it during the Reddit exodus of 2023.