After the 1st Gulf War the Americans left Saddam to slaughter the Shias; are they guilt of the same mistake...?

unfortunately yes. they have different values than us. they seem to need a leader no matter how mad or bad he is. other wise they seem not to be able to know what to do. like wolves in a pack they long to belong and take the blood from another at whatever costs, they need a leader regardless of how much they like him.