When you fight an insurgency with cruel force, especially with disregard for civilian casualties, all you do is further the circumstances that led to the insurgency in the first place. These groups are recruiting for a fight against a foreign army. If said army just brutally killed your innocent brothers and sisters, you are a hell of a lot more likely to get radicalized and join. It's certainly no recipe for post-conflict stability.

This is what is so absurd about Israel's war right now, and it was absurd about the US' war too. And I disagree that the US would've "won" if it was "ok with more splash damage".