I will give a whack at disputing it.
When Gingrich became speaker, he told told every republican congressman not to argue policy with their Democratic opponents, but to demonize their opponent as bad people: enemies of the country who wanted to hurt the country with their policies - that they were socialist communist liberals who were against God and American values.
That was a very effective strategy for the next 30 years. Because dems telling Bubba that they are NOT a godless atheist socialist will not win the day. It’s like the LBJ story about how he told his political advisor to spread the story that his opponent was having sex with barnyard animals. When they told LBJ that it wasn’t true, LBJ said “Who cares? let’s get the son of a bitch to deny it!” So debate content was no longer about issues so much as it was about God and country and “family values”
And people like Karl Rove perfected the art by having wedge issues like burning the American flag become pivotal in an election. The Republican senators and congressman knew that the first amendment gave you that right, exactly the same right as standing on a soapbox and saying, “ I disagree with my countries long-standing racism”, or “ this country sucks because our foreign policy is literally killing people who are innocent.” Republicans back then knew that the liberal position was true, but they also knew it was not politically effective to agree with supporting the constitution when Bubba wants to beat up the guy who would burn the flag. It was brilliant, because taking the mature responsible position on preserving our constitutional liberties will get your ass defeated in an election.
The second thing that the Democrats were not responsible for is Rush Limbaugh and the advent of conservative drive time talk radio, and Fox News becoming what it is. You are blaming the Democrats for not being effective communicators when the other half of the country are sworn to not listen to Democrats or any news that Democrats might be on, because it is “fake news”. The active communication you blame democrats for failing requires two parties, one of whom agrees to listen to the other person communicating an idea. They don’t do that. In fact, listening to the other side or reading something from the other side’s news source is an act of treason that is against your team.
The other problem is that there are numerous studies showing that people on the right embrace black-and-white simplistic ideology. They have no time to learn why the Middle East is not all Arabs, but also Persians. They have no interest in learning about Sunni and Shia and Wahabism - they are much more receptive to “bomb the desert into glass”, and “ make Gaza a beachside resort”.
The short way to put it is that nuance and complexity is not something they have an interest in. That is why “drain the swamp” has such an appeal. that is the only thing they need to learn to say. They don’t even have to know how to explain it to someone.
There are other tangential issues like diminishing education, a total lack of emphasis on critical thinking and the liberal arts (the biggest sin being the word “liberal”, which does not mean what Cletus thinks it means).
The other thing is the rise of the toxic fundamentalist evangelical Christian community, and their desire to push theology over secular debate on issues. If the magic sky fairy du jour tells you what rules to put on in vitro fertilization legislation, who are mere mortal democrats to oppose that?
The more the GOP took the low road the more successful they were. I do not know when it happened, but we reached a tipping point. We should’ve seen snowbilly Palin‘s popularity as the canery in the coal mine. But alas, what she was selling is exactly what the voting population wanted. If the economic crisis of 2008 had not happened, McCain would’ve likely won.
Finally, I’m not saying Democrats don’t have a lot of old and new feet wounds from their shooting. But I disagree that they could overcome those other factors. and I did not even go on a tirade against social media, another huge promoter of tribe thinking.
TL;DR
Apparently, we get the country we deserve.