You can have a git repo on a server that developers use ssh to access just with git. The bells and whistles aren't part of the core job. It's just my general griping about software these days.
I'm very comfortable with git at the command line, but I still think it's valuable to have a web interface. For instance, with a web GUI I'm able to share a link to a specific line or range in a file in a specific commit.
Typically if I need to do that I'm asking a question or requesting a change, and in that case I want there to be as few barriers as possible to increase the chances that the other person cooperates. Asking someone to clone/pull the repo, checkout a hash, and then view a line in a file is a much higher barrier than asking them to click a link.