Ah, you might say, but if Congress actually votes the Syria authorization down, then future presidents will feel constrained by the threat of a similar congressional veto whether they want to emulate Obama or not. Except that it’s actually more likely that future presidents will look at a congressional rejection in the case of Syria and see a case for going to Congress even lessfrequently than recent chief executives have done. The lesson will be clear enough: Presidents who ignore Congress’s Article I powers (Clinton in Kosovo, Obama in Libya) get away with it, while presidents who respect those powers set themselves up for a humiliation.
Read the entire entry for the (highly unlikely) impeachment scenario.
One argument Douthat doesn't make, but fits in with his logic (and would have made much more sense, to the extent that sense is to be found in the situation): The authorization for force should have been sought BEFORE the use of chemical weapons. Then it might actually have had a deterrent value, which frankly is more than half its worth.