I think they are fine if some different communities interests overlap. Otherwise all what you said is true and mostly a duplication of effort, and should probably merge communities.

Correct, they are not.

Personally I use Hugo and host it on Codeberg Pages, it is super fast and the templating system is a godsend. If I wanted an easier solution I would go into Bearblog

Some people recommend omg.lol too.

Instagram has made it almost impossible to create clients, reason why barisnta stopped developing.