"I'm not sure if continuing the Korean War would have been a good thing."
Probably not, but that misses the point. If the Democrats think a withdrawal that parallels that in Korea is without dire consequences of its own, well Korea is an example of the endgame we don't want.
There can be a quagmire of disengagement just as well as a quagmire of engagement.
I agree with you, if we simply withdrew from Iraq, the problem continues. We probably will have attacks in the USA. Jordan might be next on the list for extremists.