My view on that (which was from very low on the totem pole) is that the acquisition happened at a time where Skype's core business model (paid calling minutes) was under existential threat. Consumer communications preferences had started to go from synchronous (calling) to async (messaging) even before the acquisition came through. While Skype had asynchronous communications in a decent place (file transfer in the P2P days was pretty shaky but otherwise consumer Skype was a solid messaging platform), there was no revenue there for us.
Then the acquisition happened at a time when Microsoft presented a lot of opportunities to ship Skype "in the box" to pretty much all of MS' customers. Windows 8, Xbox One and Windows Phone (8) all landed at more or less the same time. Everybody's eyes became too big for their stomachs, and we tried to build brand new native experiences for all of these platforms (and the web) all at once. This hampered our ability to pivot and deal with the existential risks I mentioned earlier, and we had the rug pulled out from under us.
So yes I think the acquisition hurt us, but I also never once heard a viable alternative business strategy that we might have pivoted to if the acquisition hadn't happened.
