I’m well aware of the developments, but fact is that it would be trivial to support these devices, they just choose not to.
Assuming that Apple makes “informed” decisions based on the number of active devices is just ridiculous. Apart from the abysmal 2016 and up Intel-based MBP machines there is plenty of great and capable hardware out there.
Both my 2011 MBA and 2014 MBP (late 2013 model which honestly holds up way better than my 2018 MBP) have both gone out of favor [1], but they both have SSD’s and are fully capable of running 64-bit software.
Apart from the security coprocessor for touchID there’s very little difference between these and the machines that are currently supported.
As for Apples willingness and ability to deliver software updates to earlier, but still officially supported versions of MacOS - there are considerable issues and concerns [2].