I think his point is at least worth considering. This is from the interview, and it's a response to a question about why mass protests haven't been resulting in any real change:

MD: There are several reasons why I think that that isn’t happening. One is that, in my experience studying all these revolutions, there needs to be some kind of what I would call a revolutionary column, from the top down, that is moving against whatever the existing system is. And that you can have popular protests, and popular protests are a necessary component of any social revolution. But unless you have people inside the inner circles of power–what in our case would be like, the politicians in the Senate, maybe we’re talking about leading tech billionaires who are going to be able to fund things surreptitiously, the way that, say, the Duke d’Orléans was surreptitiously funding most of the revolutionary journalists that were driving events in 1789, like Camille Desmoulins–absent that kind of force inside the political structure, it’s gonna be difficult for that popular movement to translate into actual grabbing of political power. You do need somebody who’s there, ready to take it over.

MD: And you take the Russian Revolution as a perfect example. The February Revolution did not happen just because the workers in Petrograd rose up and were marching through the streets. It also happened because members of Tzar Nicholas’s own family–those politicians who were absolutely in the cabinet, who were serving as the senior councils that were powerless at the time–were all of a mind that Nicolas probably needs to be removed at this point. And so pushing Nicholas out of the way–if the ruling class elite in Russia or in France had, in fact, been united, I don’t think that those revolutions actually come off. It’s never, I don’t think ever, going to be enough to simply have people marching through the streets. You need that upper rung to be willing to move in and pop the people that are in power, and push them out of the way.

MD: And also, you need the funding for all of these things. Like Lenin was taking money. Famously, Lenin was taking money from the Germans, we know that in 1917. But even before that, he’s going and having meetings, when he’s in exile, with British capitalists who are sympathetic to the liberal, constitutionalist wing of the Russian revolutionary sector–like the cadets, people like Pavel Milyukov or then, Kerensky is a little bit to his left–that are sympathetic to that constitutionalist movement in Russia, and see somebody like Lenin and the Bolsheviks as a group who could advance that interest, which is popping the Tsar and removing him from power.

So the Bolsheviks are taking money from like, capitalist entities in the West, as a matter of course. So if you don’t have those sorts of things going on inside of your hypothetical revolutionary coalition, you have a bunch of people massing in the streets, but nothing, really, in terms of realpolitik, is going to happen. And right now you can tell how much the liberal elites in the Democratic Party, or in just sort of the liberal business sectors, are just terrified of any kind of mass, grassroots political movement. They just want everybody to go home. That’s what they want to have happen. So they can just get back to the business of going through the motions of being leaders of a country without actually having to be leaders of that country.

I read this as him basically saying you need a vanguard party to successfully carry out a revolution, and this party must have real power and influence. In the modern day US, most avenues that might propel leaders to that position have been almost completely blocked off to the left, but having key people in those positions seems like it would be critical. As timid and milquetoast as Bernie was, he was still a figure that large numbers of people were able to rally around. It feels like we really need that, but actually left. That seems tricky to pull off.