[BeetleB]

>I have seen developers spend sometimes an hour or more a day explaining to scrum masters what they just built, so that they can then go "communicate that up" to upper management or project management in opaque meetings developers aren't allowed to attend.

Your scrum masters really aren't. The SM role is supposed to be a few minutes a day, and focus more on how people work rather than the technical details.

Examples are things like telling management that the team has often missed deliverables because a key resource (some piece of hardware, etc) is often unavailable. Or even telling managers that their employees think one of the manager's policies sucks.

To an extent, it's about holding the team accountable as well: Why are some people working on a lower priority item when no one is working on a higher priority item?

Don't get me wrong - I'm no fan of scrum, and am not saying a SM is needed. But, as with management, a good SM is a valuable contribution to the team.