I recommend you check your facts before you open your mouth. Check the version of the Skype app in the Amazon Appstore. Then download that version, try to sign in, and discover it doesn't work anymore at all. :)
Because I did all of those things, before I gave up and bought a Windows device. Which isn't open either, but at least is honest about it.
No, the issue is that their current application is now dependent on Google's proprietary infrastructure, because Google has moved away from an open source application platform.
So? The point is, there is no up to date version of Skype for Android. There is one for Android-based Google Play platform, but none for Android itself.
Android lacks apps so badly it's almost unusable. People should stop calling Android open when in fact they mean Google Play platform and do not realize what's really left there when you leave it pure Android.
I have to use Skype's infrastructure to use Skype. Obviously. That doesn't mean my data should also be transiting Google's infrastructure as well. Especially if I supposedly have an open source phone.
Because I did all of those things, before I gave up and bought a Windows device. Which isn't open either, but at least is honest about it.