Imo, kops is as valid or invalid as that "balance" method. (Which, afaik, is from another voodoo whisperer Steve Hogg).

Right, nothing exist in a vacuum, and stem length and angle and bar angles and etc are all integral to your overall fit and balance on the bike when all points of contacts are active.

The tried and true methods persist, and if they apparently work for millions of people, then it must be for a good reason. It may very well not work for you individually, but it atleast establishes a good starting point.

After long enough rides, and through various terrains and intensity, I'll find whether my body and my ass tends to want to slide forward or push back from existing o baseline position...and I'll adjust base on that