The problem is, in my opinion, the make up of the US population. Here in Canada the population has tended to lean more Liberal than Conservative (in general federal politics). That is why the Federal government has been Liberal for the majority of Canada's history. In the US it seems that the general population trends more conservative. That seems to have changed more so in this century, but thanks to a lot of shenanigans by the republicans at all levels they have managed to keep power while the demographics have turned in favour of the democrats.
As such, with the help of the right wing media machine, democrats are more likely to get punished by voters for any perceived bad behaviour/decisions than republicans. I mean just look at what is going on now. Trump and the republicans are running roughshod over everything republicans pretend to care about and they are sitting on their hands leaving democrats to try and protest in the streets. Then look at the disgusting situation in North Carolina where the supreme court justice (democrat) may not be assigned to the bench because the republicans on the bench are supporting the criminal proceedings of the loser to try and eliminate thousands of ballots in a democratic district (surprise, surprise no mention of ballots in republican districts). Or Texas where the governor was not going to call a special election to replace a democratic congressman who died (again from a democratic district) and only recently, finally, caved to pressure. Yet he still pushed it to November so they have no representation or vote in congress for almost a year.
And yet, even this small sample of examples, there won't be any punishment for the republicans who are breaking/bending the rules in their favour. What's worse is that the legacy media just ignores all but the most egregious stories while the right wing propaganda machine keeps the conservative voters in the dark as much as is possible about any of it.
So, again, when there is no punishment for terrible behaviour for republicans, and democrats are more likely to be punished, or voted out, for even a hint of "liberal" wokeness, etc. I don't really see how the democrats can do much overall. I do agree though that they should use their time in power, especially when they have all three branches of government, to push their agenda hard like Obama did with the ACA. Because no matter what they are going to get voted out of the majority anyway so next time they get a majority go full bore and ignore the right.