That's the problem with "responsibilities" instead of a "mission". One changes/evolves much more quickly than the other. I see responsibilities as the "how" and the mission as the "why"-ish.

Why does Core Team do all of this (disconnected at times) work? Because (partially from what Chris quoted):
"[S]tability, security, performance and architectural cleanliness of the system" is important and this is the (only) team that can lead the work.