Open plan is good for collaboration/communication heavy types of jobs. In this kind of jobs, disruptions is a way to propagate "just in time" information through the organization. You can still eliminate disruptions in such setting, and it superficially leads to a high "productivity" in terms of LOC produced, but you act on outdated/misleading information (or you deny that information to others), which often leads to working on wrong things in wrong ways.

People often argue this can be fixed by just not needing to communicate. Like all user stories have all necessary information prepared. All the (functional, non-functional) acceptance criteria are defined, all the design documents are perfectly specified etc. But that's a pipe dream, which leads to other kinds of productivity losses.