What would be you best example of 'throwing the baby out with the bathwater'?

Forgive the politics, but the best example I can think of right now is the farmers who’ve relied on undocumented workers picking their crops, voting to have them all deported in the name of "America for Americans"—now complaining that they can’t find anyone to do the work.

There’s another idiom that fits: "cutting off one’s nose to spite one’s face".