You could say there's a left/right split in the Fediverse, or considerate-speech/free-speech split if you like, and the left side uses more Mastodon and the right side uses more Pleroma, and GS is originally largely left but got an infusion from the right the year before Mastodon. But then there are Nazis on Mastodon instances too, and communists and anarchists on Pleroma. Gay and trans people are spread throughout the platforms.
A lot of us are still here mostly for the free software discussions.
So I think the software is a pretty bad proxy for pre-screening people.