Well, in a sense, this departs from github in the sense that they try to keep everything as simple as possible (sort like the Apple design philosophy).
But developers are, or should be, power users. And in that regard a tool like this is VERY welcome. A tool that exposes some more sharp edges in exchange for flexibility.
We also try to keep things simple.
Without gatekeepers, the pull request workflow is quite the same as GitHub.
Advanced users can explore gatekeepers to achieve much flexible workflows.
Hackers may also write plugins to add their own gatekeepers in future releases. 8)
But developers are, or should be, power users. And in that regard a tool like this is VERY welcome. A tool that exposes some more sharp edges in exchange for flexibility.