We needed them to operate the structures of the government and military. They commanded loyalty from the people under them in the hierarchy. Most of those people - except for the worst of the leadership - should have been given government jobs, a steady paycheck, and amnesty.

Instead the US had to attempt to rebuild all of those structures of command largely from the ground up anew, which takes years of time and tremendous resources. During those build years, you get constant intense chaos and instability fighting you while you attempt to make progress. It was exceptionally stupid.