So, because it’s hard to lose weight, solutions that work (which are hard) get shunned and argued against?
This feels like a “the truth hurts” kind of thing. Or a “personal responsibility isn’t my problem!” thing.
Maybe that’s the whole point though, anything that requires personal responsibility and accountability is rebuked.
What's your definition of 'solution that works'? Because yes, running a calorie deficit is a solution that works (for losing weight, it may cause problems for other, perhaps more important, goals for some people), but telling someone 'run a calorie deficit' is not, in general, a solution that works if your goal is to help the person lose weight (it can actually do the opposite, in fact, if you're sufficiently obnoxious about it). It works fine if you want to just blame them for not losing weight, though.
So yes, at certain point a person is responsible for themselves, but on the other hand, if you have a goal of reducing obesity, you're not going to get anywhere by just saying 'well, everyone who's obese is responsible, and I am going to do nothing about it but remind them of it'.