It is extremely easy to switch web browser. It is not easy to switch OS. On a Windows machine, if you are savvy enough, you can install Linux, but otherwise, you need to buy a Mac in order to avoid Windows. And you need to learn a lot in order to drop Windows (easy for us here on HN, hard for 99% of people).
It's fine if you dislike some of Mozilla's decisions with Firefox. People have complained and in fact Mozilla has changed some decisions following that criticism. But the situation is just not comparable to Microsoft with Windows.
For that reason, I don't see a point to diverting the conversation. The topic here is Windows 10.