I am not relying on vote scores to prove my point, I am pointing out that a lot of people support a guide to trade. Also, there has been this demand for a much longer time. Apparently, a lot of people disagree with me on my point of view, despite the base comment having only 5 points, on a thread with 11 votes. Strange, but not important.
What is important is what you said about the differences to our definitions of "understanding trade completely". I felt it was a simplification to think that playing one spain game was enough to know every single aspect to trade. I even explicitly mentioned this in my comment. And I also felt it was rather ignorant when he implicitly said "every single aspect related to trade" (how I implicitly defined "understanding trade completely" in my initial comment) was "not really that complicated", which felt rather presumptuous and narcissistic to me, and prompted me to respond as aggressive as I did. Probably a mistake in hindsight.
I also understand your point that the work to payout ratio makes the very in-depth analysis of trade not worth it in most games. I know. I made a whole imgur album of analysis of the trade nodes as they are usually behaving, that can be applied to most games. The details are not important enough for most people. But I play many games experimenting with trade and trying to find tricks and exploits that can be useful to me and whomever I share them with. So when someone says that playing one game as a standard colonizer gives a comparable amount of interesting approaches to trade as all my efforts and many other people's efforts combined, I felt a little sceptical. But I disagree that "understanding trade completely" does not include all the little tricks and tips and exploits and things like letting native nations with trade ideas stick around to boost trade steering or planning your CN's so they steer towards trade nodes where you have more power and many more I shouldn't list off now.
What I think he meant was that he understood the trade system in EU4. Understanding trade completely is something different, IMHO.