I was taught soft field for my FAA PPL back in 1990. However, I was taught the technique on either hardtop, or dry grass which really isn't very soft.
I learned soft field at Indiantown, Florida. They get a lot of rain down there. Fortunately the grass at indiantown is about 7000' long. I was getting a checkout there in an ancient C172. Least I assume I was, it crossed my mind after that the old dude instructor could have just been an airport bum hopping a ride. Anyway, I got to the end of the runway, had 20 degrees flaps, kept it going, got to the end and firewalled it. I got the nosewheel up early, rotated back to a nose up angle, and held it. We would accelerate, then hit a big puddle and slow down. It was pretty impressive, water flinging off the wheels and hitting the wings. Happened a couple of times. So I made an adjustment, and got the nose up attitude to a little more than I was comfortable with. Same thing. We are bombing along, using up 3000' so far, and no joy. So, with another 4000' to the fence, I tried something different. I pulled the yoke all the way back, got the nose really high, then I got the stall horn going off. Then I knew I had it. It staggered off the ground, I milked the yoke in and kept it 1" off until I got up to flying speed. We burned up 4000' on that first attempt. After I found I could get off a lot sooner, though it sure took more runway than usual. Landings were fun, I would end up at the backside of the power curve nose high, plunk the mains on and keep the nose up with power.
I also flew a J3 out of there. And, when it was that wet, the J3 required really no special technique. It was easy.
So, I would maintain that you can be taught, and still not know. I bet the majority of pilots, either here or anywhere, don't do any real soft field. Not to say that some of you don't.
-- IFMU