A better analogy would be if wheelchair companies were causing people to be ashamed of using their legs and preying on a societal hatred of "walking people" and making everyone feel like they need a wheelchair to be accepted in society at all.

If weight loss things were FDA approved, effective, and didn't carry the weight of a society that tells people that being overweight (or even just feeling overweight) makes you less respected as a human being, then I'd totally agree with you that they shouldn't be banned outright. But unfortunately with how we currently look at weight loss it's not as simple.