Sure, Apple fixes their old versions... per a published schedule.
Apple, like Microsoft and most others, publishes a support timeline that says when support (features, updates, security fixes, etc.) will stop for each release. Publishing such deadlines is pretty much standard practice.
The objection here is NOT that Microsoft will stop support for Win7 in Jan 2020 and for Win8.1 in Jan 2023. They've been saying that officially for years, we accept those deadlines.
The objection is that Microsoft has quietly been NOT providing that support, for Win7 and Win8.1, more than two years before those deadlines are supposed to come into effect.
I am not aware of Apple ever doing such a thing. Whether Microsoft has done so in the past is anyone's guess.
For what it's worth, Microsoft has what I consider an exemplary overall record for providing support for old releases. They've bitched and moaned about it, but they generally have provided support for many years more than Apple or other companies typically do.
Frankly the reason is that a huge percentage of Windows users are reluctant to upgrade to newer versions, meaning support is necessary for security reasons, long past when Microsoft wants to stop it.
Apple is known for dropping support and surprising customers. Granted, I don’t ever recall anyone including Apple claiming they support something they aren’t, but Apple has no better customer reputation than Microsoft.