[bluGill]

Car mechanics care about the standard. A grade 5 bolt is different from grade 8, even though grade 8 is objectively stronger there are many places where they are too strong and so you need to use the objectively worse bolt. I don't remember the terms metric uses for the above, but there are metric equivalents for the same reasons.

[tehbeard]

That's a misinterpretation. Best bolts in the world doesn't mean strongest, that's where we'd use the word strongest. Best bolts is an opinion.

A max strength before shearing/failure is just another req. for the task the mechanic wants to know, it doesn't make them objectively worse unless they were used in a situation where they needed to be stronger.

[bluGill]

I didn't want to type in a 1000 page engineering textbook. What I wrote is close enough to make the point, but you are correct as well.