

You want all applications to explisitly support each individual filesystem? That sounds insane. It is absolutly fair to demand some common ground like posix compliance. And a windows user can like anyone else just mount their git repo area using any other filesystem.
Firefox’s default total cookie protection is the real solution for this. Yes there is a facebook cookie on reddit, but it is sandboxed from the facebook cookie on cnn and the facebook cookie on youtube.
Also the noscript extension. It takes a while for you to curate your whitelists, but it is easy to do and nothings get to run without a active considerarion.