You can still end up with a single way of thinking, but it’s less likely. Think of it as rolling D20s instead of D6s, where each number represents a given mode of thought.
Honestly, I'm not sure. I've worked in companies where diversity was seen as important but where people also liked hiring from the Universities they went to. You really don't get any diversity of thoughts with that. But those experiences are from the UK, maybe in the US color of skin says more about your character than the university you went to.
That certainly happens, but you will also find that companies - in the UK too - that insists on e.g. hiring from a select set of universities will tend to also have problems ensuring racial diversity for example. Because it's exceedingly rare that they'll have a representative distribution when hiring from a selective set of universities.
E.g. my ex works in HR for a bank that has a diversity board tasked with improving diversity. Problem: The bank prefers to hire from a certain set of universities that is dominated by students from private education backgrounds, which are predominantly upper middle class and above, which means they're predominantly white.
The numbers are such that with the universities in question they can not match the overall ethnic mix of the UK while recruiting staff with the degrees they want from those universities.
Yet suggesting that one hires by merit rather than by which university they're educated at is totally taboo to even suggest, though it'd almost certainly instantly improve their diversity and raise overall skill levels.
Companies where diversity is actually seen as important will quickly realize that they need to revise hiring policies. And one of the ways to revise it in most areas is to actually hire by merit, rather than by university "brand".