Its possible that you and I are not privy to information for something that they have planned which needed them to discard their old policies.
Most people that deal with digital ecosystems know that without platform consistency for every user, the experience inevitably gets diluted for everyone in the long run as you can't count on standardization.
As a project manager that has managed many large website and app launches in the last few years, I can tell you that sometimes you have to break support with certain things, to implement other better things. I've been part of website re-designs and re-launches with totally different layout and functionality, causing them to lose half of the audience but double the revenue. I've seen it backfire too...
With technology and disruption, if you never end up using a back up plan, you played it way too safe and you're not going to disrupt anything. Microsoft just used theirs...
If that was the case, then they still have a very big problem with communication. They were unable to express how these new policies were better or why they required the loss of the old ones. And given how they were completely incompetent in this respect, why give them the benefit of assuming their policies were well thought out and beneficial, instead of also a complete mess? The evidence points to them not knowing what they were doing.