I agree with some of what is posted there, at least about shaming and insulting people being wrong, but being very overweight ISN'T healthy, and human beings did not evolve to carry around half their body weight as fat.
As for the studies showing fat people live longer, the results were skewed by not accounting for the many thin or underweight people who are underweight due to illness (cancer, etc.). I read that awhile back, but let me look around and see if I can source it.
We tend to judge what is "normal" based on the "norm", the average of what we see around us. Today, in much of the Western world, there are many people who are obese, and many overweight people suffering from malnourishment. But just because it is "normal" doesn't make it healthy or ideal, any more than being severely underweight is healthy because it is "normal" in areas suffering from poverty or famine.
Please let me say again that while obesity IS a public health crisis and is disastrous for the health and well-being of the individual, this does NOT mean that the ideal is for everyone to be runway-model thin, or to berate themselves for carrying around a few extra pounds.
Some people are naturally very thin, and some people are naturally heavier. There is nothing wrong with carrying around a bit of extra weight if that is what one is genetically predisposed to. However, there is a huge difference between being carrying around a bit of extra weight and carrying around an extra 60 kilos of fat.
And, yes, BMI is nonsense.