As someone on the far left, I’m not a Democrat. However, from an observational perspective, I think the problem with this argument is that it assumes that the people who voted for Donald Trump are necessarily as deeply invested in party politics as is the author (and most other Democratic Party members).
While there was an obvious assortment of racists, sexists, and xenophobes among the Trump voters, a sizeable number of voters were voting out of desperation. Both of the dominant capitalist parties are well to the right of center, and have sold themselves, and the American public, to psychopathic corporate interests.
As a result, these voters were simply looking for anyone who would take notice of their increasingly oppressive lives. Their economic realities had primed them for anyone who offered an alternative to the Carter/Reagan/Bush/Clinton/Bush/Obama neoliberalism that’s been poisoning the country for four decades.
Had The Democratic Party not rigged their own primary for the purpose of engineering Hillary Clinton into the nomination, voters may have had the opportunity to vote for a New Deal-style Democrat in the general election. Instead, they had the choice between a warmongering Wall Street crony who represented business as usual; and a crude arrogant billionaire, who at least represented something different. Donald Trump was certainly a false prophet, but for many people, the risk undoubtedly was worth it.
While I really don’t care about the health of either The Democratic or Republican Parties, the Democrats are on the verge of political irrelevancy, and unless they go after the millions of voters they’ve alienated with their push into the neoliberal right, they will go away long before the Republicans.