The p2p part was relevant for the operators as Skype didn't need to run (and pay) their own servers to deal with the load, but some other user close by provided

The p2p part was relevant for the operators as Skype didn't need to run (and pay) their own servers to deal with the load, but some other user close by provided it for free, giving low latency all over the world. However with shift to mobile the patterns changed and less people ran it on desktops, thus less supernodes and the p2p approach had limitations (no group call) where solutions were needed.