Your IT graduate made their own choices - maybe they wanted to do their job and go home rather than discuss with world-class people. Or maybe they had problems with concentration or noise.
Some people are introverts, or have busy life you're not a part of and never see, or just have different priorities. It's ok.
Companies often pay for their employees to attend professional and technical development workshops or go to conferences, because part of your job is to improve your skills. Casual water cooler talks do the same thing; they improve your skills, and help initiate creative ideas that ultimately help build better things.
In my own PhD, I saw supervisors demand their students attend department get together, bar hangouts at conferences, and even casually talk to other people in the dept. If I was a manager of creative types, I would absolutely rate someone who didn't "waste their time" at work lower, because if your job description is to create, you need to do reasonable things to improve your creative skills and outputs.
Several of my employers issue staff with noise cancelling headphones on day one on the job. The employee is supposed to make the suitable judgement call on when they're suitable (needing a few hours of uninterrupted concentration) and when they're not.
The alternative is giving people offices so they can actually isolate, or understanding that people who operate on 'maker time' will not be productive with regular interruptions.
AirPods Pro are often used as hearing aids in “transparency” mode. Do not make the (lazy) assumption that someone wearing them cannot hear every word you say.
Furthermore, I think if I had to listen to self-proclaimed “world-class” engineers all day, I’d wear earphones too. And not on “transparency” mode.
I mean this 100% seriously: when you have community outside of work you spend less time chatting at work.
1) I don't know how young people meet each other in real life when both men and women self-isolate with earbuds now.
Unless taking your earbuds out is a signal you're interested?
Maybe somebody can fill me in.
2) I knew a young IT graduate who wore earbuds at work. He had the chance to listen and discuss many topics with world-class software and IT engineers, except he couldn't hear them.