> As far as I understood the reason Microsoft broke Skype so badly was because they used centralised servers with backdoors
In fairness, it was eBay that first bought Skype [1] in 2005 centralizing the data. eBay then sold it to a private investor group which Microsoft then bought Skype from [2] in 2011.
Following the Snowden leaks as well as the information from Bill Binney, NSA scoops up the data regardless..