From the circles I was in, everyone jumped from Skype / Mumble / Teamspeak because of D/DoS attacks after having their ip exposed.
It happened all the time because booters were so popular and widely available, costing about $5/mo via paypal.
People were willing to put up with more delay (over p2p) to prevent having to trust each person that joins the TS.
Skype transitioned away from p2p because mobile phones were not very powerful and they needed a lot of supernodes.
First desktop apps were the supernodes, then it turned into centralized servers entirely.
