The one thing Dems can be thankful for is that grassroots activism in their party is nothing like the beast GOP grassroots activism might one day become, if the base manages to stay active and diligent enough. The anti-establishment camps of each party have different dynamics with the opposing establishment camps.
Progressives might dislike the centrists in the DNC but they live in fear of the Republicans enough that they will still vote for the establishment, albeit reluctantly. That's why Bernie and AOC are servile creatures who ultimately bow to leadership. Populists in the GOP meanwhile have a "I'd rather spare my enemy than a traitor" mentality and they act like it. The fate of every Republican representative who voted to impeach Trump is a warning.
One big issue that the Dems have right now is that they effectively traded the effectiveness of their ground game for total control of it.
When I was still in the activist base, ages ago, the low-tier managers at the local level were almost unilaterally low-level politicians themselves. They were dudes who cares about local issues and their constituents, and would, later, be running for Town Clerk or something like that. So you'd be helping them canvas and get out the vote for a higher-level candidate, and in turn, you'd be helping someone who gave a shit actually get into office later. They'd basically sink or swim on their own from there; the DNC didn't give a fuck once the bigger dudes were elected, and it wasn't unheard of for some dude you canvassed with and later were helping run for office to be directly opposed by someone his ground game helped get elected. The internecine conflicts between local-level Dems were fucking
brutal.
Then, as was the case much later, the DNC were heavily invested with the concept of "you have no choice" as the primary reason to go with them, strategy-wise. Don't improve your candidates, don't get better candidates, just threaten that the world will be destroyed if your guys don't get in. See if you recognize a few of these gems from when I was still involved:
"Vote for us, or you'll get more religious nutjobs like Santorum."
"Vote for us, or there will be more war in the middle east."
"Vote for us, or we'll be ruled by racists."
The problem, of course, is that these threats only really hold water if you aren't familiar with the undercurrents behind each. Any problem you wanted to complain about the Neocons over - and there was
ample things to complain about - were stuff the Establishment Dems did worse. Shitheads like Santorum and friends were in the Neocon cesspit, but Bush was the one that fucking ended Don't Ask Don't Tell and was the president when Gay Marriage was legalized after nearly two decades of promises by the Dems. Neocon economic policy was and still is a shit-show, but it was a Dem that brought you NAFTA and another one that tried to bring you SOPA and PIPPA. Dubya may have been the president at the time, but the Iraq war wouldn't have happened without most of the Establishment Dems voting in favor of it, a reality they'd prefer you forgot.
In short, the threats stopped working, because the Dems happily gave us what they were threatening us with if they didn't get in anyway.
Eventually, the inevitable happened, and oldschool Dems decided to take things into their own hands, because the establishment Dems obviously weren't going to. They started pressuring via grassroots activism, running outsider candidates, and primarying establishment darlings. The DNC pretended to put a brave face forward while fucking
seething over this shit, because each time they'd have to get involved, either by destroying that upstart candidate (watch how quick Dems,
especially outsider Dems, mysteriously have sex scandals materialize the nanosecond they start trying to represent interests that aren't the DNC; it's really amazing how consistently it happens), or pumping untold millions into a race after one of your darlings gets successfully Primaried the fuck out (Joe Lieberman, for instance). By the time of Occupy, the Dems were firmly in the crosshairs of their constituents, and like the Tea Party before them, the establishment decided that this was not going to be allowed to continue.
The solution? Identity politics. It would scare off the normies and the oldschoolers, but the more aggressive parts of the base would react like you just gave them red meat. This was one of many major reasons for the shake-up in DNC membership; the hard lefties could be counted on to give the exact brainless response the establishment needed while undermining any opportunity for grassroots activism to push things in a better direction. Good luck pushing for financial accountability or economic reforms when every time you have some kind of rally, you have the dumbest motherfuckers the left has show up to let their freak flag fly. Better still, the newcomers had a tendency to sit in a position of minor power like fucking
Ryulong and use it like a petty tyrant for "the cause." Minimal ambition, willing to do what they're told, and easily denied if they got too big for their britches. Win-win-win, from an establishment perspective, though their shortsightedness would not allow them to see the danger these newcomers actually posed to their rule in the long term, though they had ample warning from saner heads they chose to actively ignore.
By 2009, they hit sufficient saturation in the DNC that they had basically pushed all the old guard out (because Entryism is a fucking religion to hard lefties), and by 2010, they had firmly established themselves. The fucking difference in the sort of emails my political contact account would get were fucking weird to watch in real time, and I'm pretty sure any Dem or Independent who was watching their correspondences at the time could relate to you painfully similar stories.