They rebelled because they don't want to do what they managers do. Decisions the managers make don't just go away because no one in charge is there to make them.
I had a job when I was in college where, in the latter days, I was promoted to a senior position in a campus computer lab that had managerial aspects in addition to the technical stuff I did before. I got that position because I knew my stuff, helped organize the lab, and was a senior worker there (in a workplace staffed by college students, it doesn't take long to attain seniority). I hated it. HATED. Worst time I've ever had in my career. The point in the semester where I was supposed to submit performance evaluations.. I dreaded that. These were decisions that would affect peoples' salaries. Affect whether they were kept on. Affect what they heard from the "real" managers. For a guy who wanted to code and set up servers and tinker, it was a stressful distraction.
I think a lot of geeks are like that. They don't want to be the manager. They don't want to be involved with those sorts of decisions. But there are so many things that a good manager will do to remove that burden from the geek. They can manage inter-personal conflicts. They can decide the direction that the department will go in. Most importantly, they can negotiate with other departments. If the tech department has no advocate who can explain in plain language the pros and cons of technical decisions, then other departments are going to make those decisions for the tech department without any input from them. I'm sure there are a lot of geeks who are now saying "oh, it's already like that everywhere." It's not. In particularly dysfunctional environments it can be, but in places where various departments have a good managerial staff, at least executives can understand what the risks involved are, and what is realistic. I understand the temptation to replace bad managers with no managers, but I can't see how "getting rid of all the managers" will improve that situation.