You say that like it's not possible to have a balance—have enough meetings and communication to properly coordinate the team, while still leaving each individual enough uninterrupted time to get plenty of flow-state work done.

The posters above advocating for flow state aren't saying anywhere that they don't want to have any communication with the team. They're saying they need the flow state to get their own work done. That's fully compatible with agreeing, as a team, that there are certain times when you don't interrupt your teammates short of an emergency—and other times when everyone's fair game, and still other times for regular scheduled meetings.

So many of the "quick calls" could just as easily wait until tomorrow, or a scheduled block of "interruptible time" at the end of the day. Saying "But I need to interrupt you now!" during a time designated for deep work means that you're optimizing for your individual productivity rather than the team's; instead, you could write your question down for later, and switch to a different task for the time being, or work around it, or research it yourself, or a dozen other possibilities.