Cars are still easier to work on than laptops in relative terms of how many parts are user replaceable relative to the total amount of parts. Regardless, changing the engine is more similar to swapping out the whole motherboard and CPU. Not something the majority of enthusiasts would ever do, but there are some boutique shops that transolant modern hardware into X60 thinkpad chassis.
Anyway, swapping an LS into a modern miata is pretty simple and it integrates well due to everything being CANBUS compatible, after a sufficient amount of adapters is applied.
And where did I say that reparability must be forbidden?
I was saying hat operations like transplanting a more powerful engine into your car is rare and difficult nowadays since grandparent made a reference to cars being easier to upgrade than laptops when that's not always true.