I've seen various "innovation" studies that show more diverse teams come up with more ideas and are more productive, but less diverse teams
think they are more productive. A quick internet search turns up
https://www.forbes.com/sites/forbescoachescouncil/2019/09/09... for example.
For software, for example, there are plenty of characteristics that some engineers may think are constant that are definitely not. For example, the number of systems I've encountered that have baked in the idea that first/last name can not be changed (even though names are changed by not only trans people, but also any married woman in many cultures), or assumed people only had 2-3 names (some cultures as many as 4 last names are common), is long. When the name is used as part of a permanent key for all other data about an individual, fixing the issue can be a huge hassle.
Sure, a product focus group might eventually point these issues out, but no one's changing their name in a short-term focus group study.