I don't think it would be. I think if everyone stopped advertising unit sales would crash.
Coke vs Pepsi is much less of a thing than the constant reinforcement that you would really, really enjoy one or the other right now. The constant reinforcement drives absolute sales, not just relative market share.
I think the problem is more that a lot of heavily advertised products are incredibly harmful to personal and environmental health. Sugar is unbelievably toxic over the longer term (weight gain, diabetes, etc) but the canonisation of the profit motive means that market morality rewards the creation and promotion of these toxic effects.
You could argue that if people want to poison themselves they should be allowed to. But even ignoring the direct social costs of the medical care required to clean up the effects of Type II diabetes and heart disease, the argument is patchily applied.
Some poisons (sugar, alcohol, tobacco) get a pass, while others (psychedelic drugs) don't. A few like cocaine remain in limbo, with nominal disapproval but tacit - and sometimes not so tacit - covert political support.
It's not just about bullshit jobs but about bullshit consumption, and the curious moral frameworks that support it.