It is entirely reasonable for management to set an expectation for two of the three between deadline, cost and features. The whole point of agile, as I understand it from "Uncle Bob", is that as professionals, developers are expected to provide information and guidance based on their professional opinion. Not only does agile help ensure accountability, but also acts as a continuous feedback cycle for developers to provide new context, information, and ideas as they surface.

I did in fact work at a company that was something of a dev shop for marketing agencies, and it was pretty miserable at times, because they inevitably expected contracts that held to all three. Cost was typically the one thing we could get them to budge on as new information came up (i.e. this necessary feature wasn't accounted for) though who actually ate the cost depended on negotiations.

I don't think I would enjoy working in a business with no management at all, to be honest. There are things that I am good at, and there is a definite perspective from which I view things, and the same applies to good managers, and there is not a complete overlap between the two. On top of that, they deal with problems that, often as not, I'd rather not have to worry about.