To make in-person connections and to present and teach in-person. I don't think it's particularly contentious to say that these things often work better in-person, even as someone who thinks remote work is best and has been doing it my whole career. Once a quarter also probably doesn't seem like a lot to people who are going to a conference every month or so anyway.

A conference every month! How do you get any work done?

By teaching, do you mean workshops/classes? We generally mentor people, but never actually tried teaching. But do most developers in your company teach?

I don't do that many conferences, but I know people who do. They do work at the conferences around meeting people and presenting their work. I find I'm more productive straight after a conference.

Mentoring people, yes. For very difficult topics that's definitely easier in person. Everyone teaches to some degree yeah. How do you level people up without teaching them?

Most of the teaching at the office involved the regular processes, like giving appropriate tasks, recommending learning materials, and collaboratively reviewing work (their and ours). And of course, answering their questions.

I never tried to teach, or have been taught, something like a course (even a mini-course) in anything in the workplace. But then again I don't believe most developers are qualified to do that (I don't mean "credentialed").