Two wrongs != right
That's great, so long as those who do wrong get punished accordingly, so that there is a disincentive to continue doing wrong. But what happens if someone's getting rewarded for it? Do you think that they're going to do anything but continue acting that way? And what message does it send to others?
Consider if I had two sons, Bobby and Johnny, and Bobby hit Johnny and took Johnny's lollipop. And then when Johnny went to hit Bobby back I stopped him and said, "two wrongs don't make a right", but I let Bobby keep the lollipop? What if I then gave Bobby another lollipop? Do you think he's not just going to steal the next lollipop Johnny gets, too?
The Republican party has placed gaining and staying in power over the good of the country, and unfortunately, they've been rewarded for it. It's up to us, the voters, to punish them for it, but we've thus far refused to do so, whether because of general agreement with Republican morals/issues, fear, tribalism, economic pain, or otherwise. The US political system is not designed to be so blindly tolerant of such gross self-interest by a political party, and we're all going to suffer for the destruction of political norms that it engenders, because doing so incentivizes retaliation in kind, not cooperation or compromise.
It means that when and if the Democrats come back into power, they will have zero fucks to give about taking Republican wishes into consideration. This is a bad thing for the country, because we need input from all sides, even the minority - and the refusal of that minority to participate in governing has set precedents that will be very difficult to overcome.