I think this conflates a bit p2p as a technical means and p2p as a means to organise control. Like, there are all kinds of products which use p2p architectures

I think this conflates a bit p2p as a technical means and p2p as a means to organise control. Like, there are all kinds of products which use p2p architectures internally to solve some technical problem - bit torrent is sometimes used inside updaters, elasticsearch organizes its nodes as a p2p network for greater robustness and scalability, WebRTC let's you make direct connections between browsers to save roundtrips, etc etc. But those are just technical details - the products themselves are still controlled and administered by a central entity. In contrast, crypto, file sharing and federated systems use p2p as a technical means but they are also administered in a decentralised fashion, where no person or entity has ultimate control (or should have at least). I think Skype was falling squarely in the first category here: They were experimenting with decentralised network protocols, but the nodes were all pretty clearly belonging to a singular and centrally controlled product. That's why p2p really just was an implementation detail that could be replaced by a different technical architecture by a simple update. (Weird thought as an aside: I think most companies or organisations follow a sort of similar pattern: They are communist with respect to coworkers of equal status ("everyone should chip in for Carol's birthday present"), authoritarian with respect to management and owners - and libertarian/anarchist with respect to the outside world ("freedom! ...from annoying rules and regulations..."). But that doesn't mean leadership necessarily follows communist, authoritarian or anarchist principles when deciding strategy)