The comment was not about heterogeneous or not. It was about Ph.D. or not. Everything else equal, I'd prefer a heterogeneous bunch of Ph.D.s to have designed and built the thing that's put inside my brain over a similarly heterogeneous bunch of "I've taught this myself in 1 year using youtube". Snobs or not.
Ph.D.s are trained in two things. "Reasoning about an unknown" is one of them. But the particular niche knowledge they acquired while training this is the other. That niche can save my life if the niche matches the thing to be implanted into my brain. No matter how many youtube-educated wannabe-experts take issue with formal education.
(I have many issues with the academic system, but this kind of critisism is ridiculous.)
Would you rather have a team of 10 PhDs and 3 "self taught hackers" or 13 PhDs?
It might just be me, but I actually feel more comfortable with the former.
If you ONLY hire people from specific backgrounds, you get blind spots. That's dangerous. Excluding anyone without a PhD should not be expected to improve safety.
That makes it sound like Ph.D. graduates are a homogenuous bunch. That's nonsense. Somebody with a Ph.D. degree is just that -- a person with a certain degree certifying a certain competence. Apart from that, it does not say anything. Not what background the person has, how they think, what they like. It's part of a Ph.D. degree to aquire knowledge and skills alone. "Self-taught" if you will.
The distinction you make does not exist in that sense. The only actual difference is that the "extra" 3 Ph.D. graduates have had a certification for a somewhat structured education in some research field, while the youtoube fans don't. So, everything else equal, that group has an advantage.
Everyone having the same background opens you up to blind spots, that are arguably worse IMO when you're trying to put things in human brains.
Also, PhD EEs != competence.