> Proponents of in-office working and open plan talk about the benefits of spontaneous conversations. For me I find I just can’t get anything done in these environments

Kind of depends on what you work on. As a programmer, getting a task of designing and implementing something, obviously needs a lot of quiet time. But for creative projects like video games where you're basically creating art together in team, it's really hard to do "deliberate communication" for longer stretches of time and not end up blocking everyone left and right, especially in non-AAA teams, where you basically have to collaborate non-stop so everything can move forward.