I agree that team interaction can be productive. (I might even be a bit cynical in saying that most team interaction is not, but that might be a digression). I think the distinction is in how the work culture manages those interactions. My previous job wanted open-door policies; what that turned into was a poorly managed ad-hoc set of interactions. Open door interaction tended to foster unproductive venting and it can become like corralling cats to refocus that energy into solving problems. That may be fine for a supervisor; it's probably not the best use of time for front line production person.

I think I may disagree about the "somewhat weird obsession" with uninterrupted work. (I'm assuming your '8 hours' was hyperbole). The research seems pretty clear that interruptions are more detrimental to highly focused work. I don't think it's unreasonable to expect certain blocks of uninterrupted time if the type of work requires it, but that shouldn't be conflated to someone expected to simply be left alone all day.