Playing the devil's advocate: then you still need somewhere that people can get the current repository state from. This place might not need to do anything with pull requests or any other write action on the repository, but somewhere to clone from is necessary. This would then be the "hosted" repo, and the patches sent via mail are just that, patches.
Sounds like you're talking around semantics. Yes, any server you connect to as a client to clone a repo is "hosting" that repo. But that can be practically any computer it doesn't need to be a _dedicated_ host in a server farm, it could be a devs laptop.
