It's true that it's possible to be obese and (metabolically) healthy, but nonetheless upwards of 80% of people who are obese also have metabolic disorders, and active measures taken to reduce obesity very often improve the metabolic disorder. There are very good reasons for this, given the metabolic signaling of fat cells--it's not a surprise, even if we need to learn more about the differences in signaling in metabolically healthy high-BMI individuals.

As other commenters have mentioned, being obese can also be hard on joints (whether or not the person suffers from metabolic syndrome). And there are cardiovascular risks that aren't simply a result of hyperinsulinemia.

The bottom line is that obesity is bad for most people. This is as clear, medically, as "smoking is bad for most people". There are some puzzles about individual variation, but there is no serious doubt. Exercise helps, but it's not the whole story (see, for instance, https://academic.oup.com/eurjpc/article/29/2/e50/6105192).

So, what to do? People go to doctors and are told this stuff--maybe just plain "being obese is bad for you" not "it has an 80-90% chance of being metabolically bad for you" and if people were better with nuance maybe the doctors would know and say it more and the patients would absorb the information and go "whoa, I'd better do something" not "I'm sure I'm one of the 10-20%". Anyway, people go to doctors and are told that their weight is a health risk (which it is), and tons of people still don't change their behavior. The non-lucky ones tend to develop health complications and die early (how early depends on the severity of metabolic and other disorders).

The health advice doesn't work, but people are dying.

But fatphobia works better, you say.

People want to lose weight because of fatphobia, even though they can't make themselves want to because it increases their chance of disease and death.

Fatphobia saves lives.

So your article, despite concluding the opposite, makes the case for increased fatphobia (but targeted at obesity, not at the high end of normal or "overweight"). People feel the pressure. It will save lives. (It will also lead to a bunch of people feeling guilty and still not doing enough to make a difference, which is pretty rotten, but I'm not sure that's a big enough downside to stop trying.)

It's a shame about the people who might be unfairly disparaged despite being healthy. And it's an even bigger shame about the subset of those whose bodyweight is recalcitrant to the normal methods that change it (and not the commercially-profitable but usually-ineffective stuff). But arguably, carving out an exception for people who are demonstrated to be in good condition would be preferable to relaxing the pressure and letting millions die early.

Now, that said, we generally let people do things that are bad for their health if they really want to. Given that obesity is comparably dangerous to, and comparably controllable to, smoking, the appropriate level of social pressure would probably be comparable to the social pressure to not smoke.

We do need to shift from being idolizing thinness (which for women especially tends to be at unhealthy levels) to fitness. That would also save lives--doctors tell people to exercise too for all the non-weight-related health benefits, but do people listen? Not so often. But fatphobia is arguably doing the right thing (albeit largely for the wrong reason).