It's not. Somewhere along the way (at least in US) there was a "movement" for "body positivity", which is great, when applied reasonably. It should be "we all have things we don't like about ourselves, but so does everyone, so love you". That's totally reasonable. That's healthy. That's fantastic for younger people who see all the "influencers" and "models" or fashion images, and feel bad about themselves.
What it turned into was "no matter how unhealthy/obese you are, love your body, and be outspoken about it". So, regardless of being 400lb, incredibly unhealthy, and doing major damage to yourself, love and be proud of your body.
Hell, some of my most formative years were the heroin chic era. It's equally damaging, in the opposite direction. At least women's clothing models are looking more and more like "normal" women, in a lot of cases.