1. When a client does not share its bandwidth its stops being a part of a peer-to-peer network. It becomes a part of a client-server set up.
2. The fact that the server is not fixed doesn't make it a peer-to-peer system. Example: when you watch a video on Youtube, the video isn't streamed from a fixed server. This doesn't make Youtube or whatever client you use to watch it peer-to-peer.
3. Where do these "no fixed servers" come from? Do they magically appear out of nowhere? No. They are some servers that people set up as servers, so this means that:
3.1. If Skype were to retain its peer-to-peer architecture, it would rely on Skype users to be knowledgeable enough to set up their servers (and to turn off peer-to-peer capability in the event of poor machines and unreliable networks).
3.2. The servers by necessity would have to be on desktop computers. Even in 2011 it was apparent that the desktop traffic was rapidly declining, as more and more people were switching to/using mobile. It means Skype would have to route more and more traffic through fewer and fewer nodes. Oh, and yes, those nodes would also see their data plans drain (as not everyone in the world is on unlimited plans). Or — surprise! — set up its own servers, which it did.
3.3. On top of that Skype was en route to ditching peer-to-peer even before MS acquisition, as peer-to-peer architecture had been the primary cause of at least two major (unpredictable and uncontrollable) outages that could easily be avoided with a centralised setup.
You're aware that in the original Skype peer to peer network, there already existed supernodes that performed most of the heavy lifting that you could opt out of being promoted to, right?
2. The fact that the server is not fixed doesn't make it a peer-to-peer system. Example: when you watch a video on Youtube, the video isn't streamed from a fixed server. This doesn't make Youtube or whatever client you use to watch it peer-to-peer.
3. Where do these "no fixed servers" come from? Do they magically appear out of nowhere? No. They are some servers that people set up as servers, so this means that:
3.1. If Skype were to retain its peer-to-peer architecture, it would rely on Skype users to be knowledgeable enough to set up their servers (and to turn off peer-to-peer capability in the event of poor machines and unreliable networks).
3.2. The servers by necessity would have to be on desktop computers. Even in 2011 it was apparent that the desktop traffic was rapidly declining, as more and more people were switching to/using mobile. It means Skype would have to route more and more traffic through fewer and fewer nodes. Oh, and yes, those nodes would also see their data plans drain (as not everyone in the world is on unlimited plans). Or — surprise! — set up its own servers, which it did.
3.3. On top of that Skype was en route to ditching peer-to-peer even before MS acquisition, as peer-to-peer architecture had been the primary cause of at least two major (unpredictable and uncontrollable) outages that could easily be avoided with a centralised setup.