Do they check them at all or just install them truly OOTB? If the latter, then that says that the minor things wear in. But nothing in the above statement says that it is worth any time and $$ for checks; it just says that the valves and springs and keepers don't fail, the seats stay in, etc. Seriously not trying to bust on anyone; the question is, is it worth having any checks done, or can you really just bolt them on with 99+% confidence?
I agree that some of the stuff said on the net is very, very likely not true; that is why I mentioned the shims being in place on our heads; I read one claim that they were all missing. It could happen, but is not a very likely thing to happen with so obvious an item!