You might be overestimating the influence of the Twitter Democrats. The most vocal have an outsized impact in primaries, but far less impact on the general electorate.
Actually it isn't the Twitter types.
I love going to Vegas every do often and gave found myself there in October several times. Blackjack tables are social and being Canadian people open up to me. From all over the country. Same at the bar stools.
There is imo a deep undercurrent of resentment for the Iraq war lies. For the Bailout. Against the Healthcare system.
When banks get a bailout with taxpayer dollars and then foreclose on 5 million homes people notice. And just the ones affected but family and friends as well.
When 60% of all bankruptcies are medically related the same.
Add in the opiod crisis, infrastructure crisis(why is clean water now an issue in numerous places and not just Flint?) While Washington forgets and the anger is there.
I heard it and felt in conversations.
There is a large group of Americans who don't vote because a candidate they want to hadn't been put forth in a long time.
Senator Sanders is that candidate imo.