My team is about 8 people, but we work on about 15 projects, some with about 3 FTE, some take up a few hours per week of one person on average. It happens that someone works on a project on his own for months at a time. There is some shared tech between them, but also a lot of specific stuff.

I thought that was the kind of situation he meant, where people zone out because they don't work on that project, but who knows.

You shouldn't assume too much about the environment other people work in.