i should add further reasoning is that many of the people i see on masto soc... are very obviously into the idea of abusing children. i don't just mean "ew they're icky pedos", idgaf if you're a paraphile so long as you don't intend to harm (thought crimes do not exist). but these people very clearly either say or just boost posts from people who demonstrate they want to abuse children for real.
so, yeah. i just don't trust open registration instances like that.