I think the key point of the line you quoted was "for extended periods". Obviously flow states are useful, perhaps even required in some contexts, but to demand a full day of uninterrupted flow-state engineering bliss is IMO unrealistic and very often counterproductive. Software development at the company level is a team sport, and being actively hostile to necessary communication simply because it "interrupts your flow state" is the act of a prima donna or "rock star" developer. I've refactored a lot of code/been doing deep design work and been interrupted during said work. Did it make my personal task take substantially longer to complete due to the task-switching/getting my flow state back? Sure, but the interruption was for a good reason and my help was actually needed. On balance the interruption saved the company money and time because the drop in efficiency of execution for my slice of the pie was less impactful than what my help was needed for.

Now if you're getting constantly pinged for stupid shit that anyone could Google, then perhaps you should politely confront the person(s) doing so and make your expectations clear rather than declaring a pox on all interruptions.