They could prove their case by actually doing it at commercial farm scale. But as far as I know, no one has. Which, to me anyway, shows they're probably (but not certainly) wrong.
On paper Mark Shepard seems to have about 106 acres around his house, which I think is a gross branding mistake, because he farms a lot more land than just his homestead. I have to find this interview again because it was kind of shocking and I'm afraid I may be misquoting it. One interviewer got him talking about all of the land he owns elsewhere, leases, or consults on and he makes some comment about he may actually be managing more farmland than anyone east of the Mississippi.
Most of us are on the internet all day regardless. We downplay the incremental cost of both doing things, bragging about it online, and getting it on people's radars, like it's simple but we mostly think about the people who are good at it and not all of the ones who quietly disappeared without most of us ever learning about it.
Farming is exhausting. Farming is remote. Farming is slow, and experiments take years to prove to be more than dumb luck. The gap between killing it and selling your audience on the notion that you are killing it is much, much wider. Talk enough, and you have to stop doing, which means you're now selling ideas that you can't back up.
Understand that it is my wish and hope that these sort of low/no fertilizer organic techniques can work better than "traditional" heavy-fertilizer/irrigation farming the west now mainly employs. It's just that vaguely recall hearing about this sort of thing 30 years ago. And 20 years ago. And 10 years ago.
I have created fully automated systems for indoor that control everything except harvest. It is impossible to convince people due to the cost I am pretty sure.
Thusly? Money printer really does not go brr for this.
Some of his crops are targets of opportunity. They're a cover crop and if the weather is just right and he gets it planted in time, he might be able to harvest it, or at least graze some livestock on it, but if not, then that's fine too, because the dividends still made it worth doing.
He is a very frugal farmer, both in resources and energy. Mark Shepard, in contrast, seems to be more interested in the energy side of frugality, and is so open in his disdain for people throwing good money/time after bad that it's practically his personality. In particular he likes to rant about how utterly mathematically unsound the idea of rain barrels is, and the kind of cognitive dissonance it takes to keep telling yourself otherwise.
Rain barrels make a tiny bit of sense in a small urban lot with a large roof. They make no goddamned sense at all in most agricultural contexts.