It was based on my real-life experience working with a colleague from another team.
> If it were possible to use itertools, wouldn't they just research that, update the PR, and say OK in a comment?
Time spent on a call is time you are publicly perceived as working. Time you spend researching itertools is time during which someone can interrupt you by pinging you in Slack. In that employee's shoes, it seems clear which one of those gives you less of a headache at the end of the day.
Politics aside: Exactly what you describe - the capability to research a library, respond to a PR comment concisely and appropriately - are skills that no one learns during a CS degree, nor doing code monkey work. Ideally, this is the sort of thing a junior engineer gets taught during their first years on the job if supported by a capable mentor. But if they don't have one? Tough.