While simply eating less works for most people I think this is a little dismissive of other factors at work in the obesity epidemic.
Eating less actually works for all people, it's just hard to commit to. Restricting calories is uncomfortable.
The advice "eat less move more" is a proven loser. Not really even a question. Time to move on. Maybe low carb/IF/less time-consuming HIIT will do better. But we know move more, eat less has failed. Being more smug about the fact it would work if only all these dummy pilots would use it right isn't going to improve the public health success rate.
If people are less able to comply with a program than an alternative program, then the first program, in fact, works less well (if it can even be said to work at all) for them.
So the two halves of this statement are opposed.
If you look at statistics from Europe at the end of WW2, or from the late 1930s in the US, how many obese people were there? Pretty much zero, because food was scarce.
Without getting into the discussion of whether or not your problem is simply equivocation because you are interpreting "unable" in a different sense than those using it (or, e.g., the medical community) would in this context, "eating less" in the context of this discussion was eating less volume of food with the same calorie density, and the post to which you responded was pointing out that that is, in practice, not as successful for some people as eating similar volumes of food with lower calorie content.
Both of these methods are equally "eating less" in a caloric balance sense. The set of processes that affect processes related to wait loss (including both processes that control how much of that energy content is actually made available, and processes that might be viewed as compliance-related in terms of satiety triggers on the input side and processes that make people prone or resistant to activity on the output side) have substantial, well-known, biological variation between individuals, which have significant linkages to propensity for obesity.
Treating the issue one of simply calories in vs. calories out with success outcomes differentiated only by moral features like willpower is a stupid statement which is proven false by a vast body of research on metabolism, obesity, etc.