Roy Moore won a Senate seat despite, in July, not having heard about DACA or Dreamers. He also asserted there are places in America under sharia law, but when asked for specifics came up short. Likewise Trump won the presidency despite having a deep and abiding wellspring of blissful ignorance.
You could say this is proof the Republican party is the "stupid party", as Mark Shea gleefully used to say back fifteen years ago. And that's probably true now but I think there are a couple other underlying trends.
Just as if you want to be a conservative SCOTUS you have to try to not leave a paper trail, there's an advantage for a political candidate to be ignorant of policy. You can lie freely, without pain of sin. Thus Obama can run a campaign for '08 on just the slogan "hope and change!" and pass ACA by subletting it all to Congress. And Trump can promise, "the best health care for everybody will be easy!" and mean it, believe it, and sell it.
I recall someone asking on a EWTN Q&A forum asking why tell people about mortal sins because one of the conditions is that they must know it's mortal. Similarly, if a candidate is completely ignorant he or she is more free to dispense their reality-free point of view.
The other underlying factor is the ongoing atomization of society.
The surprise is not that political parties are dying but that they lasted so long, since nowadays joining a group is passé. If you can’t even get players to stand for the national anthem it’s no wonder politicians won’t stand for the muck of a political party. “Cooperation” is a swear word.
Just as we have 10,000 Christian denominations, we’ll have a hundred completely independent senators - everybody will a McCain or Sanders or Paul or Moore.
My guess is that state governments will become more important in the future given how useless the federal is.