I don't believe for a second that Google engineers on the ground are the cause of these problems. Most Google engineers are pretty genuine and have end users in mind. But the decision to block YouTube on WP is not an engineering decision. It is an executive decision.
The fact the changing the "user agent" string alone makes it work fine is enough to show there's no engineering difficulty blocking it.
I wonder what would happen if one day users found their Chrome won't run no matter how hard they try, and Microsoft simply say they from now on Chrome is not supported.