It's like... You have gangrene in your foot and someone says that you should amputate it to save your life. But you complain that you want the foot healed and functional, not amputated and the gangrene keeps spreading further and further and soon you are going to have to lose the leg or die.
This is not the perfect metaphor for politics but my point is that you sometimes need to make tactical decisions and vote for someone with a chance of passing even if they are only slightly better than the other alternatives.
Doesn't do much good to say "I did not vote because Hillary wasn't any better than Trump" now does it? Similarly if Romney is at least better than the other guy vote for him rather than wasting your vote in the gerrymandered areas.
Romney would only be better than the other guy in the Republican primary.
As for why I rag on the Dems so much, it's because they've been offering the same sort of milquetoast, corporatist, neo-liberal centre-right candidates for decades now, and especially over the last eight years, it's cost them literally over a thousand seats--look at how many state houses and Governorships the Republicans now control, not to mention the Presidency, the House of Representatives, the Senate, the Supreme Court, and let's not forget all those vacancies on the lower federal courts.
They have not, of late, tried running populist left candidates
en masse, even though populist left policies almost universally have well over 50% support and the most popular politician in the country is a populist left one (by US standards, anyway; most anywhere else he'd be a centrist or centre-right). So why, when your strategy has so clearly failed, would you keep doing that and not try the one thing neither party has tried on a large scale, when you know that the most prominent figure who espouses precisely that is incredibly popular--who can get roomfuls of rural Trump voters in supposedly solidly-Republican states to cheer his agenda?
From a Narcotics Anonymous text in 1981: "Insanity is repeating the same mistakes and expecting different results." (Earliest known occurrence)
The Republicans keep doing it with trickle-down economics. The Democrats keep doing it with corporatist centre-right candidates.