@ngn the guy behind sr.ht, Drew DeVault (aka Sir_Cmpwn) blogs a lot about the design decisions behind it. the "git." prefix is because (unlike gh, bb etc) it's a set of interacting services. The bugtracker is todo.sr.ht, the docs in man.sr.ht -- and they work together but can be used/hosted independently.
Also, I've been using various Unixes daily since ~1990, but I only learned why "~" stands for home last year....