And when Apple designed their products, they get to decide how to design it.

You can do whatever you want with your computer. But nobody has to design it the way you like it.

What happens when you indirectly cause the machine to fail by installing some shout 3rd party part? Are you still going to claim warranty? Walk into an Apple Store to ask for help?

We have the https://en.wikipedia.org/wiki/Magnuson%E2%80%93Moss_Warranty... to rely on.

Huh? Explain more.

Generally speaking companies are not liable for failures due to the customer's own modifications to the product.

Practically speaking, however, they are liable for the time to service those customers and diagnose product issues to determine that the customer was at fault. And, that extends to any future buyers of used devices. And, any resulting displeasure from customers, even though it wasn't Apple's fault.

These sorts of things are exactly the types of problems that exist in the used car market, for exactly the same reasons.

Yep. That’s why I think Apple tends to lock down their spare parts.

What about a work computer? You're not the owner, but presumably you appreciate when can feel that your work computer is still secure.

If it's owned by the company then I don't care what they do since that's no longer my responsibility.