So you're saying it's impossible to fly a straight line from point A to point B in a crosswind, or to steer a boat in the same sort of straight line in a constant current? That's just not right. It is probably true that in a real stream, rather than the ideal one we're imagining, you are likely to follow a curved path, because the stream will not really have the same velocity near the shore as it has in the middle, and because you never know the exact speed of the current and so guess at your initial heading and change it when it's off, as it usually will be. In the ideal conditions of the example, though, the boat will go in a straight line right across the stream. And planes fly straight lines from one place to another in crosswinds, by crabbing, without following curved paths and without holding, or even changing, rudder positions, except when the winds differ from the forecasts.They do it every day.

None of this is advanced in any sense. It's the sort of thing you learn on the first day of instruction in dead reckoning. Every full scale pilot has to know this stuff to get a license. Denying it is pointless.

Your 35 years of hands on experience has surely made you a skilled aerobatic pilot. Nobody questions that, and nobody is "bashing" you. But, as Sensei himself is fond of pointing out, with sufficient practice you can become very good at aerobatics without ever learning even the basics of how an airplane flies, or elementary facts about the effect of wind on airplanes. I know some RC pilots, whose flying looks great, who believe that turning downwind causes a plane to lose airspeed, which is the dumbest myth in the book, but they can fly models spectacularly. In the very small spaces we fly in, while making constant corrections, that sort of knowledge isn't absolutely essential. But when people ask, they should get the right answer, not just a guess.