Then don't.
> if you think the obesity crisis is fake/blown up
I don't think obesity is fake or overblown. That's what the article was trying to argue.
I do however think BMI has its flaws and that those flaws are pretty significant when it comes to assessing individual health.
> Being fat is bad for your health... it is healthier to be thinner than obese
There is a healthy body fat % range but it is all very dependent on someone's activity and consumption.
The amount of body fat being detrimental doesn't change if you just exercise more or eat healthier. It's still bad by itself. You might have a better life expectancy than someone who is a sedentary lump at the same body fat, but that isn't saying much. Hence, again, BMI is a gut check. If you're at BMI=27, you almost certainly need to lose weight. Period.
While this is not untrue, I don't understand why people single out BMI as a measure to criticise. No measure is perfect, or even particularly good in many cases, and yet it's BMI that gets it.