That's an extreme case, but the point still stands. For example, right now, I'm pretty fat, because I haven't shifted the weight I gained over COVID. Even though I'm visibly way larger than I was, I'm not much heavier than I was pre-covid, because I've lost a heckton of muscle. It's insane to me that BMI will look at me pre-covid, and look at me now, and say "that's the same picture". Especially because I personally found that the best and safest way for me to lose weight was to focus on getting strong and fit first.

That's because BMI is actually pretty good as a screening tool. It's easy, simple, and pretty damn accurate when combined with an eyeball test. To the extent that it misclassifies people it is far more likely to underclassify obesity than overclassify. The people complaining just don't want to hear it.

We ran into it a bunch in the Army. As well as the fat over abs phenomenon. Very few of our BMI failures were actually fat. The Army test was really problematic because they measure your waist and neck. So you're simultaneously trying to lose belly fat, build neck muscle, and maintain energy levels for infantry training. Which is just a bit of a nightmare to be in. Meanwhile every week you're running 30-35 miles, putting 15 hours in the gym, and doing 10 hours of field exercise, all on top of any infantry training.

I think it's one of those things you either run into a lot or very little.

I bike and rock climb, I walk long walks and overall in a good shape, not great, not terrible. When the doctors see my bmi without other metrics, they immediately tell me to lose weight and don't take anything else seriously. I missed very serious illness because of that, every symptom I had was thrown into a pile of "your bmi is bad, lose weight", until one doctor was smart enough to check on me for real.
BMI is incredibly oversimplified and gives lazy or overworked doctors easy way out of doing their jobs, which kills people.

OH, come on, I have body close to some professional shot putters or hammer/discus throwers! /s

I'm not a top athlete but I do lift weights and according to my BMI I'm .5 under overweight despite my body fat percentage staying in the 15-17 range. I'm not even that big.

The problem is that it incentivizes fat over muscle.