I think you’re misunderstanding what most of them keep practicing. It’s not the kooky cranial/cervical manipulation(you can make an argument that them having to learn that stuff in the first place is BS and a waste of time), but most do pick up a few muscle pressure point tricks and stretches that are essentially the same as what PT instructs patients on how to do. Is it bullshit? No more so than most medicine that’s practiced(the data behind the vast majority of what your average physician does is at best all over the place, the truly “settled” clinical questions are few and far between). In my book though, anything that keeps you from having to prescribe a scheduled drug (read as:narcotic or muscle relaxer) to get someone functional from something like severe trapezius tightness or piriformus syndrome is a heck of a tool to have at your disposal in a primary care or urgent care setting.
I mean, you CAN make wine out of Concord grapes, but it still tastes like Concord grapes after fermentation. Many places that lack the more temperate climate of France or coastal California make a lot of wine out of Concord and similar grape varieties bred from native grape species that are in many cases more disease resistant and tolerant of extreme temps. Overall, they tend to be sweeter wines(though concords technically have a lower natural sugar content on average than many traditional varieties) and often they get mixed with other fruit wines (blackberry, blueberry, strawberry, and even another native grape called a muscadine) because they aren’t easy to extract a lot of tannins out of, and are a real one trick pony from a flavor perspective. Many attempts have been made to breed grapes that exhibit more “traditional” wine flavors, to varying degrees of success.
That being said, this is some real prison hooch territory and there’s zero reason to do something like this with as accessable as winemaking kits are these days. Now if you’re in a prohibition type scenario maybe it makes at least some sort of sense.