I think open plan offices started to become a thing in the late 90's just before the first dotcom crash. At least that was the first time I encountered the concept codified into a formal term that everyone was throwing around. That, and "management by walking around" (which i think was the pre-cursor to "stand up meetings".) Anyway, I hated the open-office concept then and I still hate it now. Its noisy, distracting, invasive...it really made me miss cubicles. I can't believe it took a worldwide pandemic to get people to reconsider them...