While I agree with many of your points, consider that ALL aftermarket improvements to engines/suspensions... happened because of DIYers who had the intellect to see the shortcomings in the OEM design and the ability to improve on them, as opposed to starting from scratch. Many eventually became OEM over time
Not a fair analogy. One poster here was making recommendations the equivalent of "you should rejet your carbs" when the car in question could have fuel injection. He doesn't know what might need improving since he has never seen or heard one. The poster was GUESSING that he could improve the Porsche because something worked on his Pinto.
In short, he doesn't know