Having already broken Linux audio (PulseAudio) and booting (SystemD), he wants to break home directories. The fact that Red Hat still employs him tells us a lot about Red Hat's business objectives and complete lack of concern for things like community decision-making, simplicity, UNIX/BSD/POSIX compatibility, recoverability, and reliability.
The OS shouldn't even know about users. Should be all capabilities (capsicum, CloudABI), and an auth service just hands out what it thinks the requester is entitled too.
It's funny to see the systemd ecosystem every so slowly go towards this design.