It's not wrong for a developer to use Windows, but it is wrong for a company to impose it, or even to have it as the default option.
I agree with the only caveat being if the dev shop is working on a platform-native stack (like .NET or iOS) - in which case you obviously have to use the 'family' platform for consistency and to be able to obtain all features (like being able to compile + emulate an iOS app - which can only be done on a Mac).
I agree with the only caveat being if the dev shop is working on a platform-native stack (like .NET or iOS) - in which case you obviously have to use the 'family' platform for consistency and to be able to obtain all features (like being able to compile + emulate an iOS app - which can only be done on a Mac).