I think the statement that Rails might of gotten further on the windows platform is a ridiculous statement. Ruby as far back as remember is a language that prefered environment was Linux. There was a point where there was no windows version. I remember when even on OSX the installation of ruby was an endevour. OpenSsl incompatabilities, gems with c extensions that never worked right (rMagick which is a Linux first lib). So the underlying language that backs Rails is not windows friendly. There is no doubt in my mind that Windows would have been a hindrance not a positive.
Macs are only popular because for the most part they are similar enough to Linux that you can develop on a Mac and deploy to Linux. I don't know of one Rails shop that chooses to deploy on Windows.