A lot of BBQ folks out there don't know what's going on (science); they only know what works (method). And since nobody pulls those tough BBQ meats off the smoker at those temps, they never really NEED to know what happens at the lower temps. BTW that's not a criticism--there's a world full of BBQ cooks who make AMAZING Q without knowing those things.
I can say I've got empirical evidence that you can get tender results well below 160*. In fact, my wife's favorite way for me to do ribs is 149* for 24 hours sous vide, and only put on the grill to sauce them. Tri tip at 130* for 24 hours then seared on a grill will be INCREDIBLY tender. I actually once did beef short rib at about 135* for 48 hours (don't recall as it was a decade ago) and seared in cast iron and it was more tender than filet mignon while cooked medium rare.
Note: I don't recommend all those things. Ribs are the only ones I still do that way. I prefer tri tip traditionally cooked even if it has a little more chew, but it's still quite good that way. On the other hand, those short ribs, while insanely tender, maybe still weren't the most appetizing texture lol.
I view it like brewing. Learn as much science and as many techniques as you can. But then the craft is knowing when to apply certain techniques, and when NOT to apply others, in order to get the desired final product.