It's awful for consumers, though. And for developers, it's not great, either, because you end up having to support a customer on an old version of OS X, for example, which means keeping a suitably old environment around just so you can keep your builds compatible, or jump through all kinds of hoops.
I don't feel like this is a good thing to encourage in an industry that already has more than enough churn as it is.
I've never run into that issue, ~90% of our users are on iOS8 or above. With iOS you can safely support the current version and last version while only pissing off 2-3% of the customers which is exceptional compared to most platforms. I also do Android development, Don't even get me started on what a mess that is, complete opposite..
I don't feel like this is a good thing to encourage in an industry that already has more than enough churn as it is.