Skype used to be peer to peer. Your call went from you to your friend (whomever). Microsoft decided that they couldn’t mitm that setup to scrape data; so, soon after they acquired Skype, they made all calls go through their servers.

Then they tried to make Skype make more money, since those servers aren’t free. Then they made teams and copied half the code into that, and cludged the rest to make it hold together.