Well, we all already know alcohol does more harm than broccoli. If that isn't enough to stop someone drinking it, why would cancer warning labels?
While most people have some idea that alcohol is had for them, the link between cancer and alcohol is not widely known. This is also reflected upon in the article.
While it may seem like "smoke is smoke", that doesn't appear to hold for marijuana - and it's not clear why.
But later when vaporizers got popular they changed the tune to "tobacco is bad, no matter how you consume it". Honestly, I don't know which is true.
Nobody chain smokes joints all day unless they're Snoop Dogg or something.
There are many somethings out there. But vapes are indeed more convenient.
To address your comment about nicotine, vaping nicotine salts (what is the standard now; juul, vuse, etc.) is a huge upgrade from cigarettes. My lungs have literally healed. My doctor (who disapproves but admits the difference) and I would love to see a reply refuting this.
I'd also like to point out that the Canadian Cancer Society (one of the groups highly involved with advocated for labelling) has also issued statements about inhalation (of any substance). So they quite literally have done the thing that you accuse them of having not done.
Raising the prices of cigarettes beyond the means of poor people and passing restrictive laws about smoking in public and private were the only effective strategies against smoking. The warning labels were an intermediate justification, and in the case of Swedish snus, actual misinformation.