It sounded from the example like the code under discussion was quite simple, "ten lines of code". So it's plausible your "look at & investigate independently" is allowed to happen, and should take less than a few minutes, say, and then this interviewer is inviting them to walk through things in a shared manner.

In other words, from my perspective, you're not actually in disagreement with their method. They weren't saying "narrate in real time as you're first having [thoughts]". Practically nobody does that ever, or is expected to do it, except in other practices like mindfulness or therapy and what have you. They were saying they ask them to understand it, explain it, and then talk about improving it. OP's problem was with the candidates whom couldn't understand the code, and weren't even willing to talk about the state of their understanding so that the interviewer might help them walk through things further...

>I don't have any source but from my experience mathematical/computer minded people are more likely to be introverted/talk less then arts people.

I think you are right about that, but that just means that if they want to be effective members of a team in an organization, they need to work on their communication skills. Ability to communicate is something you can learn to do better.

I know this for a fact. I used to teach public speaking, and students came out far better at it than they came in. The same is true for many other communication skills. See for instance Marshall Rosenberg's book Nonviolent Communication, which is great for interpersonal conflict situations.

In fact, I think a lot of introversion is at least in part due to poor communication skills that could be improved with training and practice.

I studied engineering and went to an engineering school (EE, ME, CE, etc). I have had contact with many engineers on a daily basis, although I do not do this work anymore myself, and I have found that engineers can talk very well - actually I have never met one that can't and/or won't (the real problem is getting them to shut up). So in my experience, smart useful people are always able to communicate. There may be the occasional savant who is awkward or such but I have not met them.

As for programmers - same thing. If they are any good they are more than able to talk the talk.

The article explicitly notes, though, that most excellent programmers were also excellent communicators.

Effective communication doesn't necessarily mean you talk a lot or are extroverted. It means that you say things that matter when they matter, and that is a crucial skill to have in almost any work environment.

Having a high signal-to-noise ratio is (obviously) also critical to communicating successfully about code / technical issues. Talking for the sake of talking or waxing poetic about the understood 5% of the problem at the expense of the 95% remainder is a negative signal too.