Shells are supposed to inherit a ton of state from their parent — [e]uid, groups, working dir, env vars, nice, umask, chroot, ... This takes zero effort in uni

Shells are supposed to inherit a ton of state from their parent — [e]uid, groups, working dir, env vars, nice, umask, chroot, ... This takes zero effort in unix, but would all have to be (securely!) re-implemented to be able to send code to a shared execution daemon... And I expect the right implementation for many of these params will be running separate daemons anyway (eg. you clearly want one per user).