I'm mostly okay cleaning out a lot of legacy and unsupported devices. In some ways, and for people who want to support really old hardware it may not be great, but they're most likely stuck on older versions for other reasons.
I disagree. They are dropping support because nobody is maintaining them. There may very well be people still using these features, but they haven't been motivated or aren't properly skilled to offer to maintain them going forward, and haven't motivated some other skilled person via payments.
Rather, the core difference is that Apple does not offer a way to have external people take over providing support.
Support for 486 is another thing, but, frankly speaking, running a modern Linux kernel on a 486 makes no sense, either form a practical or preservationist / museum perspective.