But it's funny you mention that as I think that may have contributed to the issues I was having, along with the other factors mentioned. I was literally just about to say what you did. Obviously you need to hold on the handle bars or you'd be balancing JUST on the pedals, but I think there's a difference between doing that and actually PULLING the handlebars. My theory is that by pulling, you are not balanced like BW's article mentions (still need to pull it up on my computer to fully dissect it), and all that keeps your bike from coming out from under you is a fulcrum, in the form of a root or a rock.
Really, I just wanted an excuse to post pictures of Tracy Moseley ;-) I went to a clinic where she was teaching, and I've had a girl crush on her ever since.
Some of these articles (I've been reading through a bunch because I've forgotten at least half the stuff I've been told) also talk about the ability to move your fingers on the bars while you're riding, to demonstrate that you don't have a death grip on them. You know, because you don't have enough movements to think about while you're riding down rocks. You really want weight solidly rooted into your feet (which should be at 3 and 9 - don't watch my terrible habits in this regard), so that your hands are light on the handlebars, just enough to guide it. And of course your butt should not be touching the seat, and certainly not using the seat as a chair (again, don't watch me - I tend to avoid getting off my saddle until the last possible moment).
This position with the butt back behind the seat can be a lifesaver. Today I was riding along and suddenly realized I was about to go down a rock drop I wasn't expecting. No time to brake. I was able to jam down my seat dropper button and sit on the saddle to drop it, then got my body back, looked straight ahead down the trail, and let the bike do its thing. Without me interfering, it happily clattered down the drop and then let me take charge again. You're right that my arms were not locked out; they were slightly bent, hands loose on the grips. The feeling is definitely that your weight is in your feet. And eyes forward is critical - if you watch your front wheel, you're going to endo.
There's a point in jumps and drops where you have to use more advanced techniques than just getting back, but I haven't ridden anything like that outside of controlled clinics with built features (run up the hill, go off the jump, get told I still wasn't doing it right, etc).