> Why would I buy a computer that's crippled like that?

Because I want a computer. I go to the store, I see a cheap one, and I pay for it. Then I go home and use it. I'm an end user that just wants to get to email, youtube, and Google. I don't know what secure boot is, what a BIOS or an EFI is, all I care is that I don't have to spend money.

I don't know it's crippled. I have no way of noticing. Hell, I'm still using Internet Explorer.

If you're corporate you buy it to make sure that the OS and Drivers are both signed by the people you bought them from, and thus nobody has tampered with them.