The thing to consider here is Stack Exchange is a company that serves geeks, and is built by geeks. Naturally the culture and values of the company are going revolve around developers. But for a huge chunk of the companies out there everything revolves around sales and marketing. The actual role and importance of developers varies from company to company but very few of them are going to revolve around them in the same way. At many they're an afterthought.

While there is no "typical manager" it's safe to say that if you sample any given company and take all their managers and executives you won't find a lot of coders. Executives don't sit around talking about Rust vs Go, because it really isn't that important to their business most of the time. So they really have no idea what it's like to be a coder, and probably don't take up a lot of cycles thinking about it.

Most jobs do benefit from collaboration. Development is no exception, however too much socialization and interruptions kill us. This is what they fail to understand on most levels. They see sales, marketing, and other groups that benefit from being able to swivel a chair and ask a question and automatically assume that it will help developers, since they "never meet their deadlines" anyway.

So in my opinion the push for open offices for coders is mostly out of touch thinking, a little need for micromanagement, and of course being able to show off work being done for people taking a walk through. How that affects developers is of little concern.