PRs are useful, and so is the discussion system. These things are at par with other platforms that are pretty much equally barrier-free.

Any of the workflow automation stuff might be more difficult to replace, but I haven't had an especially good experience with it anyway. I don't know about everyone else, but it's been pretty unreliable and fragile. Even the Azure integration, which ought to be first-class, is pretty opaque. I really wanted to lean into that stuff, but for now, I'm happy running my own.