At least for me, one of the reasons I buy Apple hardware (e.g. iPhones) is that they’re supported longer than the competition. So I think if Apple are doing the above then it’s short-term thinking.
My Dad bought an 5K iMac in 2017. He just used it for browsing, email and YouTube etc. It works well. Very fast. Fantastic screen. Doesn’t support the new OS coming out in a few months (but presumably will still get security updates to its existing OS for a few years). There is no reason to fill our landfills with powerful machines like that! (I would say I regret telling him to buy a Mac, but Windows 10 will stop getting security updates in a few years too.)