Look at it this way, BMI is a cross section of weight and height. I was considered "overweight" for ages because I just had tree trunk thighs from hiking and weightlifting. Like, less than 16% body fat but told I'm 'overweight' every time I got weighed.

The ruler was fucking wrong.

Nowadays, I'm much more of a fat fuck so the ruler is right now but only just so... I'm still under 25% when using hydrostatic!

i think you’re taking that quote out of context a bit. a few sentences later, the article says

Even physicians have weighed in on the shortcomings of B.M.I. The American Medical Association warned last year that B.M.I. is an imperfect metric that doesn’t account for racial, ethnic, age, sex and gender diversity. It can’t differentiate between individuals who carry a lot of muscle and those with fat in all the wrong places.

“Based on B.M.I., Arnold Schwarzenegger when he was a bodybuilder would have been categorized as obese and needing to lose weight,” said Dr. Wajahat Mehal, director of the Metabolic Health and Weight Loss Program at Yale University.

so the point they seem to be making is that, while BMI is controversial partly because people like to shoot the messenger, it’s also just not a reliable measurement in a medical context, even as a heuristic. the article also goes into more detail on its other shortcomings as well. the article also indicates how BMI was never intended to be used in a medical context. so, there are plenty of valid reasons for wanting a new metric.

but i do think the sentence you quoted isn’t really doing the author any favors in terms of trying to communicate the central point of the article.

it’s easy to calculate but extremely rough. Efficacy varies immensely. Look, nobody’s forcing you to do anything, I’m just saying that BMI is way too rough to be seriously examined.

Or just make a better ruler?

my main beef is that "too fat" is a wildly varying scale from person to person because everyone stores and processes fat differently. and if you're "too fat" that may not in fact be your most relevant health concern. my experience with health providers that focus on BMI during intake is that if you're "overweight" many other health problems will be seen through that lens even if they're unrelated... in my case, lots of dieting advice, being told to exercise more come to find out decades later I had an undiagnosed nervous/muscular condition. now that it's treated somewhat, my weight stays pretty much in "normal" BMI with the same or lower activity. I'm kinda pissed it took this long to get treatment for an underlying condition because the ruler said "too fat."