I'd say preventing a nuclear war is pretty damn stabilizing across the world.

To be sure, there is plenty that the American empire can be criticized for. But if not the American empire, then whom? You think that power vacuum wouldn't be filled with something worse? Look at the contenders. The US, with all its flaws, is preferable. I am not endorsing American evils, but keep in mind that this kind of trivialization of geopolitical realities is unwise. It's better to focus on repairing what the US does wrong instead of suggesting that the entire empire must fall without thinking about the resulting clusterfuck that would ensue.