I have recently received a second hand Dell Inspiron 5558, which is a 5 year old model, for ~$250 for a relative
I ran updates over a few days and hey presto 20H2 installs!
My own HP x360 ENVY is a bit over 3 years old, was >$1,000 new and still hasn't even updated to 2004!
I don't particularly want to go messing around with removing drivers + random internet registry hacks to risk breaking it.
HP make their devices with the cheapest software they can hobble it with and then effectively abandon them as soon as they're off a shop's shelf.
MS couldn't really care less as attempting to work this stuff out for a third party hardware vendor with a fourth party device manufacturer from 3+ years ago is hardly worth while for them (one of the downsides of a CI/CD OS, at some point you have to assume everyone has a deployment environment that supports what you're delivering as latest and greatest).
End result?
All three companies have already made their money, so the customer gets shafted.
"Go buy another $1,000+ pile of plastic and exotic metals you cheap hippy"