This is exactly right and why corporate leaders are increasingly focused on diversity as a metric they manage to.
Essentially they have realized that many recruiting and hiring functions are underperforming, in that they are rejecting, or allowing others to reject, talented candidates who they should have hired.
And what they are realizing is that it is much harder than it seems to avoid this kind of error. Which means that even though they can see the opportunity you mention, they're finding that their companies can't seem to seize it.
Generally speaking, everyone involved in hiring is doing their jobs in good faith; there are very few mustache-twirling villains to be found and defeated. But every single person has preferences and biases which, even if essentially harmless on a personal level, can still create significant effects in the aggregate.
So leaders are trying to boot-strap more diverse cultures by managing to the outcome. It's far easier to reward a hiring function for increasing certain metrics of diversity, than tell them something like "be less racist and sexist when hiring." I mean, the vast majority of people would rightly take offense at that kind of guidance from their boss.
The hope is that in the long run, increasing staff diversity produces a broader mix of preferences and biases, which in aggregate reduces the skew against certain talented candidates. As you say: a compounding effect.