Well, that may have been their reason but I had excellent service on Skype prior to the acquisition super nodes and all and absolutely rotten service afterwards.
So whatever they tried to fix it didn't work. Of course this is all from a European perspective and the broadband situation here could not be compared to the US at the time (and in some places still can't).
From a US perspective, quality ranged from fantastic to awful to non-existent depending on who started a call. If you learned who had the best hosting, then always had them start it, you would be fine.
I gather my experience is not an outlier, which is probably why they switched.
So whatever they tried to fix it didn't work. Of course this is all from a European perspective and the broadband situation here could not be compared to the US at the time (and in some places still can't).