That's correct, but as a parent said, this kind of issue is very rare. I can't actually remember another mac os upgrade actually bricking machines. I may be wrong, though.

What's way more common is random hardware failures, unrelated to the OS. I've never had to deal with apple support and hope I'll never have to, but HP enterprise support isn't frictionless either. A colleague of mine had a swollen battery, which wasn't user replaceable (guess not only Apple has bright ideas). He called up the support, which went relatively fine but in the end he had to send the computer in for repairs for two weeks and was advised to save his data as the machine would be wiped. Luckily removing the SSD was possible and didn't void the warranty...