My take is that it's a standalone business consideration: Apple users are more inclined to pay for software (definitely the case for iPhone vs. Android, although I haven't found a source for Windows).
just from my own anecdotal experience, it's easy to prioritize apple because apple users are not only more inclined to pay for software, they're more inclined to use it.
even on web apps that are exactly the same across platforms my experience is you might more signups from windows users because somebody told them "hey, you should check this out", but the metrics on actual usuage usually favor the mac users.
