And it also helps me refine my earlier point. Too often I hear cynics (who are, after all, just disappointed idealists) effectively argue that we should give up, the game is rigged, and they'll get away with it no matter what we do. As emotionally safe as this position is, it's also self-fulfilling, and ultimately gives the powerful ever less accountability.
That said, I think "meaning what you say" should be an element of accountability, too, but you're right in that it's not strictly necessary.
I would say doing so is fundamental to consequentialist [1] and especially utilitarian [2] ethics. I'm not saying those are the best, but they are somewhat common.
How do we measure if someone means what they say?
As for the more philosophical stuff, I think I'm talking about (retributive) justice, and even more specifically, about how public attitudes about justice have a self-fulfilling effect on justice. My hypothesis is that cynical views on justice tend to be self-reinforcing, and idealistic views of justice are also self-reinforcing.
The primary utility of the cynical view seems to be personal/emotional, but comes at the expense of taking pressure off of the world to be better. I suppose my goal here is to encourage disappointed idealists to take up the idealistic mantel, and learn to get disappointed in people again. It's painful to care, but the pain is worth it to produce a better world.
This is a false dichotomy. Why do either? The alternative is not pretend that people mean what they say and not give them a pass on their hypocrisy.