You are assuming “diversity is worthwhile” is the same as “diversity alone is required for success”. No one is saying that companies can outcompete based on diversity alone. But that doesn’t mean that diversity is not worthwhile.
In fact, several companies do not even do things that have been shown to be worthwhile in outcompeting. You are assuming people in companies behave like perfectly rational automatons who will do exactly what is required to outcompete.
I don't know if you're being disingenuous on purpose or if you've just not clear about the parent's objections :
You are using "worthwhile" as "(morally) worthwhile (for (an appeased) society)".
The parent is clearly stating that, for a corporation, the main goal is to make money by out-competing its rivals. Society is not relevant, here.
If such goal was reached by diversity hiring (no need to add "only" : if this policy added even 1% to the end goal, that would be a net positive), laws wouldn't be needed because, except for the most racist ones, companies would be fighting to get all those racially diverse people.
Tech companies percentage of indians or chinese workers are very high without any coercion.
The simple reality is that talents can be found anywhere but that everybody doesn't have the same amount of talent.
