They have such a lock out feature on all their other portables and desktops too in fact (activation lock) so I’m mostly surprised it didn’t “naturally” carry over

How would locking them to the owner make them harder to use? They're smart enough and have designed enough software where they could trivially allow the user to share them if desired- that is the only "inconvenience" I can image it would cause.

I doubt they either didn't think of it or that it wasn't suggested frequently.r