Another daemon for managing control groups

> Really, how is this different from today where if you want to use this kernel feature you have to have your software talk to the kernel and twiddle it. How is it different than iproute2 or iptables?

iproute2 and iptables are happy to sit on a system and only be used for the parts that you want them to be used for. They don't try really hard to force you to do things a specific way and push you to replace a bunch of other tools if you use them.