Yes, you will be able to find studies that suggest chiro works for back pain. I will be able to find studies that show it does not. The best evidence, which is systematic review-level evaluation of all such studies that takes risk of bias into account, is the Cochrane review I’ve already cited, which shows that overall the literature supports only minimal benefit from chiro for lower back pain, comparable with massage or rest. This is how medical science works, and the problem with it, of course, is that anyone who doesn’t like the conclusion is free to ignore it and claim the treatment works no matter what the research says. Things a lot less reasonable than chrio, like homeopathy, reiki, and prayer, all have studies which their proponents claim show they work. Do you believe everything if there are any positive studies? If not, how do you decide which to believe and which not to believe? Personal experience? Plausible theoretical mechanism? How do you make these decisions?
As for the mechanism, that is a somewhat separate issue from whether or not the therapy works, which is why I listed them separately. It is clear that there is no established mechanism to explain chiro, since the VSC is a fiction. That doesn’t mean chiro doesn’t work, and if there were robust clinical trial evidence showing it did, then we could decide that without having a mechanism. This is true for some well-established therapies, though nothing like the “vast majority” as you claim. However, the absence of a mechanism IS a weakness of claims for chiro, and combined with the balance of the clinical trial literature being against it, I think it is unlikely to be much more than an expensive massage with a lot of, as even you admit, nonsense attached to it (such as the large number of DCs who oppose vaccination, for example, or the subset who recommend colon cleansing, herbs, and all sorts of other quackery).
Bottom line is if people want to see a DC, that’s their business, If they care what science says, they will find that there’s little reason to think it will help them, but not everyone care what science has to say.