The thing is, if addresses are scarce, you do need something (typically a kernel) to allocate them. Port numbers on a single IP are scarce. IPv6 addresses, if e

The thing is, if addresses are scarce, you do need something (typically a kernel) to allocate them. Port numbers on a single IP are scarce. IPv6 addresses, if each machine has a /64 though are not, and it becomes much easier, each (64 bit!) pid can have its own IP with neither being reused, so routing can be dumb. (And/or encrypt everything, keys are not a scarce resource either).