Was putting the authorization for invading Iraq into the hands of the President a strategic mistake?

Excellent observation. Congress has 'delegated' many of it's powers to unelected people to avoid responsibility for bad decisions. They have delegated to Administrative agencies rule making authority when things go well they take the bows, they they go bad they put the responsibility on to the agency. Congress has delegated the power to coin money and set interest rates etc. to the Federal Reserve, so now congress delegates the power to make war to the president. It is nonsense, congress should be forbidden from delegating it's enumerated powers and start taking responsibility for their decisions. But as long as the voting public are fooled by their BS, they will probably continue to play this shell game.