Hell if you really wanted to you might even be able to make an argument that, with hindsight, Microsoft saved Nokia by letting it gracefully jettison it's failing phone business, get a much needed cash injection, and refocus on other parts of its business.
[0] Of course some argue that Microsoft actually took over the day Elop became CEO, and everything he did was part of some plan to sink Nokia so that Microsoft could buy its phone business on the cheap.
But i don't believe it was a grand plan from MS to screw Nokia so they could buy it..
Some even suspect that MS just bought Nokia because Windows phone was not selling and Nokia was loosing money, so MS was afraid Nokia would turn to Android and they would loose their flagship devices..
So they needed to ensure a phone maker for Windows Phone and wanted go into making their own phones, Nokia had a good brand that they had a good relationship with and Elop was still there to make things easy..
On the other hand, if Nokia had focused on Android from the start or at least had devices on both systems, they had the potential to be the leaders on Android phones by now..
It was a costly and useless move.