I think it's because the different platforms are incompatible, and a large compatible community of software is a value multiplier (both in terms of the longevit

I think it's because the different platforms are incompatible, and a large compatible community of software is a value multiplier (both in terms of the longevity and the usability of your code). You want people on your platform. Similarly, it takes time and energy to master a new methodology, and that's time/energy not spent if other people work the way you do. That, and ego.