Nothing if you like electing rat a President and super majorities in the House and Senate. So many rats that sweeping change like the Great Society can be passed unchallenged.
The whole "extremism is not a vice" thing after the Cuban missile crisis probably didn't help.
I don't know if any Pubbie could have gotten elected after the JFK assassination. And Goldwater was reviled by the media just as much or more than current Pubbie candidates. He never had a chance in the court of public opinion. Back then the media was much more lib-dominated than today. No internet and no conservative talk radio.
Goldwater's stance on the Civil Rights Bill didn't help either. The GOP was losing black voters, but Goldwater's stance put most of them permanently in the Dem camp.