Naglfar
As Naglfar devours us all
The BMI is utter nonsense, ignore it.
You're wrong, but it does have limitations. It's mentioned right there on the website, but for athletes, lifters, or people who just have different proportions, it can be off. I use it as a general guideline, it's pretty good for finding a target weight if you're just trying to lose some pounds.
Don't matter who came up with it. Works within reason. The modern BMI was redeveloped sometime in the... uh I don't remember. 60s? Maybe 70s? Anyway, it's not some authoritative measure of your health, just a quick way of looking at someone's overall fitness.