I agree, you shouldn't listen to people on Twitter.
But the problem with this statement is that we, as a species, evolved to deal with scarcity, not surplus. We also had considerably more active lifestyles throughout our evolutionary history than we do now. Having so much food available that you would consciously eat less to stay healthy is a very new development- our bodies simply aren't designed to deal with constant surplus, especially at the lower activity levels.
"Eat what you want" works fine for some people, especially those that remain active, but I wouldn't call it sound advice for the general public.