Disclaimer: ex Skype employee here While this simple reasoning is appealing, I have to disagree. Both its premises (Skype was peer to peer before MS) and concl

Disclaimer: ex Skype employee here While this simple reasoning is appealing, I have to disagree. Both its premises (Skype was peer to peer before MS) and conclusion (MS made it a client-server system because Evil). - Real peer to peer on internet is not really possible, since most end users are behind NAT. Skype resorts to a number of hole punching techniques, but really only uses STUN/ICE, effectively using super-nodes as relay for sessions. This directly means that all these communication are transiting through a third party, and not peer to peer. - Super-nodes used to be regular end users (with some simple algorithm to elect as supernode users with high up-time, high throughput. Fun fact: only windows client users were possible super-nodes). This model proved to be too fragile. In case the network falls down (which happened some years ago), then the super-nodes are no longer available, and get instantly DoS when coming back up due to every other node trying to get back. This is a vicious cycle in which the network cannot get back up. So for a long time now (before MS) super-nodes are just backed by Skype-hosted servers in data-centers. - Thin clients are a real thing in e.g. the african market, where a lot of very old phones are still in circulation, no "apps" are possible. Think of your old Nokia 3310. - Persistent group chats. Users wanted it. - And on a more "political" aspect: MS needed to promote its cloud infrastructure (Azure), lower its physical resources fingerprint (get rid of Skype datacenters), and unify its technical stack (Linux/C++ now Windows/C#)