> The difference is that you can buy the upgraded parts from a third party. This has always been difficult with Apple.

Not "always". This is an artifact of the MacBook Air modern "appliance" era of Apple (and laptops / computing in general) where thin and light bodied laptops and compactness are the highest priorities, prized above self-service, upgradability, etc.

PowerBooks, by contrast, were amazingly and easily upgradable. You didn't even have to open up the case to do a memory upgrade — the keyboard just popped right up.

Two decades ago, the Framework laptop would have never needed to exist. And for the most part, likewise with Hackintoshes.