It is obvious that the #NeverTrump folks failed to exercise influence, otherwise Trump would never have been nominated as easily as he was. Their arrogance in condemning Trump supporters was still a factor in energizing those supporters, as was Hillary's stupid 'deplorable' comment directed at millions of voters she needed to attract to win the election.
So of course, failed political tactics are ineffective, but unless people want to perpetuate failure and defeat, they need to recognize and accept responsibility for their failures, and be willing to change.
What I am seeing instead on both sides, (but most often on the left) are people doubling down on the very mistakes that contributed to their failure in the first place.
With Democrats, that behavior is what has led to their historic electoral collapse at all levels across the country over the last eight years in most states.
I wouldn't call Trumps nomination easy, and #NeverTrump didn't really gain steam until he already looked likely to win.
As far as the Democrats, I do agree with you on that. I've been saying much the same for a while. Nevermind the FedGov, if they continue at their current speed, they will lose enough statehouses for the GOP to be able call a Constitutional Convention. Even if you look at their House representation, it is easy to see that they are basically the party of NY and CA, and exist primarily to spew identity politics and collect donations from wealthy coastal donors. They also lack principles, and thus, lost the last election to the bigger showman.
That they have kept the same leadership (and forget the DNC, Pelosi is the real party leader) shows they aren't even serious. They will just work off Trump's actions to rile up their base and collect funds, and probably fail again, unless Trump trips on a Rust Belt third rail.