Her writing tells readers: this moment fits into a familiar historical script, the bad actors are intelligible, and your existing moral framework is sufficient to understand what’s happening. The content is often alarming, yes, but the script itself provides emotional stability.
Again, I think we are in general agreement, but I would characterize the function of her writing somewhat differently. Here I am admittedly drawing mostly on my own reactions, with little other basis for my view, which is always dangerous but anyway:
One of the most frustrating -- perhaps the most frustrating -- aspect of the Trump administration is the way it makes resistance feel futile. It's because our tried-and-true strategy for social change has been speaking truth to power. It's how minorities of intellectuals have been able to effect social change. It works only so long as people care about the truth. Obviously MAGA doesn't, and Trump and his council of demons even less. So that's why people feel like we are screaming into a void. That's certainly the case on this message board, and also one reason that some of our MAGA friendly posters get as much attention as they do. It feels like a rare traction point, except we don't get traction.
HCR is basically performing a speak truth to power ritual. I wouldn't call it reassuring, and I don't think people take from it that our issues are historically precedented. I think it scratches an itch. It's an invocation of the way we used to do things. I'm not sure people take reassurance from it. It's more like a family prayer before a meal, or going to church perhaps. My wife talks about church as her sanctuary; it doesn't give her reassurance so much as a break from the bullshit.
There's considerably overlap between my description and "reassurance," so I really don't see this as disagreement so much as different emphasis.
On the plus side, you could also perhaps make a case that it's community building, in sort of the same way that QAnon built communities. QAnon turned out to be vital to MAGA; it created a new set of grievances and power narratives that allowed people who feel isolated to belong. HCR is maybe doing something similar, though with facts and not obvious nonsense.