First, that doesn't seem to be what the article is saying. Second, I don't really believe that it's true.
When I say "don't believe that it's true", I'm saying, "I don't believe that the removal of managers necessarily gets work done faster." I'm not talking about programming specifically-- I'm not a programmer, and managing programmers is not my expertise-- by my general experience is that a lot of people think managers are just wasting everyone's time, when the reality is more that most people don't understand what managers do. Unfortunately, this sometimes includes managers.
A good manager often spends his day trying to figure out how to remove obstacles so that the people he's managing can just do their jobs. For example, the summary says, "The article encourages managers to let devs contribute to the process and say 'No' if the specs are too vague." That sounds right to me. First, a good manager will of course listen to the people he's managing. That doesn't mean doing whatever they say, but when I have managed programmers, I assume that they know what they're doing better than I do, so if they say there's a problem of some sort, there's a problem of some sort. I wouldn't always go with their recommended solution, but would I listen to their explanation of the problem and try to come to a solution that addressed the programmers complaint as well as meeting the business needs we were trying to address.
If specs are too vague, that seems like the sort of thing a good manager would help to work out. For example, I might suggest talking to the programmer, trying to figure out which aspect of the specs are too vague, and then meeting with the stakeholders to try to clarify the specs. I wouldn't necessarily make the developer get involved in the process of clarifying them, since unless they're needed for the discussion, they probably have better things to do.
But being a good manager is pretty difficult in general. It's often not clear what needs to be done, or how it ought to be done, and it's your job to figure that out. It's pretty much impossible to be a bad manager without annoying people, but even the best managers might seem annoying or clueless because you don't see what they're doing for you. Sometimes good managers are only noticeable in their absence-- when they go away, you suddenly go "Oh jeeze, things are falling apart a bit here. How was it that we never had these problems before?" And the answer is, you were having those problems, but your manager was dealing with them when you weren't paying attention.