Good engineering decisions are always based on the big picture like long/short term goal, budget and deadline. By keeping those in mind, an engineer can then go and understand task priority, and decide which solution might be best for each task.
If an engineer team understands the bigger picture, they can in most part self-manage and figure out what to do to achieve the end goal.
However if a manager or PM shields engineers from those bigger pictures, it becomes much harder to make informed engineering decisions on individual tasks, or how to allocate time among those tasks, causing slipped deadline and over budget. This reinforces the impression that managers should provide closer guidance on what to do.
In my experience, most technical manager/project manager will only talk about the bigger picture when pressed, and only some are able to describe it clearly.