I don't have a home server yet but I'm exploring and sometimes I get confused about some posts here.

For example I saw a post asking for recommendation for a "self hosted budget management app". Can't you just install this type of app to your phone or pc? What's the purpose here, will you host it and access it from a browser? Or do you only want to backup its data to your server?

I hope I don't sound stupid please enlighten me.