I would not say a terrible generalisation, but more an honest observation.
I am a Microsoft developer, but I make a hell of a lot more money from the hardware I design and all my hardware runs Linux, so you think I would be religious about Linux. I also do a lot of cross platform dev with java that runs on Windows, Linux and Mac. I don't have a preference, I just use what works, and I earn an income for making stuff work for people. You want me to write software your favorite OS, then I will do that without conviction as long as you are paying me. If you are religious about a particular OS and you are paying me, I will tell you what you want to hear.
But, if you want my honest opinion on something so you can make an informed descision, then I will tell you they way it is. I use and make a living from Windows, Linux, OSX, IOS, Android and some other OS's that most here would never have heard of.
Opinionated nerd? Maybe, but at least I am educated and informed on the products I am discussing.