There is diversity and then there's "diversity". This is ultimately a Americentric political movement. You only see American demographics as targets, ignoring the vast number of immigrants and foreign students that enter the industry.
When is the last time you heard someone advocating for more linguistic or geographic diversity? If these diversity advocates truly care about these studies for something other than political gain, they would be at the front lines advocating for more H1-Bs.
Paypal's cofounder made the argument for homogeneity in the book Zero to One. Not only were the founders of the typical demographic mix but they were also ideologically similar. They were all libertarian and all believed a digital currency would displace the US dollar. That was a very fringe view 15 years ago. They were fantastically successful, even after Paypal. Many other successful teams are 100% Asian or 100% Jewish in early days.
I love working in diverse, multi-ethnic teams, but based on what I've observed more diverse teams seem to be a wash at best in terms of results in the US and are a significant liability in China (possibly due to the demographics of the target market).
Possibly the most egregious example in the US would be Facebook. Not only were the employees narrow demographically, they also went to the same schools, were all in their early twenties or teens and the CEO publicly said like it was important to be "young and technical" and that young people were "just smarter". From everything I've read about it, it was basically run like a frat while it was bulldozing all competition in its path. (Snapchat appears to be a sequel of this story)
What sorts of problem-solving did the study look at? Is there a way to reconcile it with the conflicting outcomes from basically all the hugely successful startups except for Slack (assuming its founding team was diverse)?
When is the last time you heard someone advocating for more linguistic or geographic diversity? If these diversity advocates truly care about these studies for something other than political gain, they would be at the front lines advocating for more H1-Bs.