> Why would that matter?

Reliability? Why should we want to centralize things unnecessarily? It's nice as a fallback but then so too is P2P.

If your message goes though my infrastructure I can shut it down when I feel like it but even if I really don't want to do that I still might be forced by other parties commercial, private and state owned.

You shouldn't need any kind of permission to send a picture to your mum sitting next to you on the sofa.