At the very least, ads should be banned or require nasty images like tobacco products.
Opposition to bans is sort of a libertarian dogma, they say bans never work and only make the problem worse or introduce new problems, and usually cite alcohol prohibition in America. But a lot of bans do work, and even that one apparently succeeded in reducing alcohol consumption even if it did empower organized crime. What's more, it's pretty easy to ferment alcohol in your basement but it's a lot harder to hide fields of tobacco. Political dogma never captures the nuance of reality.
No, that's not what we say. The primary argument for it is because we do not subscribe to a utilitarian morality. If we know that some decision leads to better outcomes from the POV of general quality of life and the like, we still wouldn't support it if it trampled individual freedoms, because we consider the latter to be more important.
It's not a difference of opinion over whether a certain theorem proves true or false. It's a matter of different set of axioms altogether.