Earlier quoted context omitted.
I am not sure how "unreliable" the peer to peer model was. From what I remember it's always been perfect for me. Media uploads could have been solved by a server-based "media" service, while keeping the reliable & battle-tested P2P architecture. As of currently, the server-based architecture is an absolute disaster, way worse than P2P.
I regularly had whole chatrooms that wouldn't update for days. I had no way of knowing if a message I sent would really like... ever... get delivered. I've been a pretty big Skype user in the past, and still use it a bit now, and it is actually so much more reliable now that Microsoft runs it.
With P2P it would sometimes take a bit longer (10 seconds?) but it would always work. When it wouldn't, it was because of a problem on either one of the endpoints, and switching network connections or rebooting the router fixed it.
With the current model it would just randomly not work (the client also sucks and sometimes hangs in an inconsistent state after the failed call attempts), without anything we can do - it's something with the software and/or servers.
I used to trust Skype calls to actually go through - now even if I see "ringing" I have no faith in whether it's actually ringing on the other side (and if it was, whether the call would actually connect once picked up).