I think you don't see them as defending alcohol because your comment is doing the exact same thing.
Also, to clarify, drinking alcohol does NOT equate to making one's life shorter - that's not at all what the article discusses. Moderate drinking may have no effect, or even a positive effect, on life span.
How about the prosocial effects of low doses of ketamine or other NMDA antagonists such as PCP and dextromethorphan?
Perhaps I'm anti alcohol because you can get the exact same effect from compounds with better risk profiles. Alcohol is a very old drug with a lot of risks compared to the benefit. It hammers so many different receptors, the off target effects are nuts and that's not even mentioning the risk from the toxic metabolite acetaldehyde.
There's no reason to use ethanol with so many better options for the same behavioral modifications.
I personally find libraries incredibly relaxing, but I assume what you mean by "it's not the same" in that a library doesn't serve highly rewarding GABAergic drugs.
People enjoy drinking alcohol because it is rewarding and most have learned to like the taste through the association of that neurological reward. That's generally what enjoyment is, association of reward with an activity. There are many other activities and compounds that are just as rewarding or relaxing but society is conditioned to accept alcohol as the default it seems, at least in some communities.
As for your last point, that is absolutely not true from my experience. Whenever I discuss the risk of cancer that's associated with alcohol consumption the other person generally has no idea, that has been over 90% of my conversations on the topic.
Optimizing your life strictly around maximizing potential lifespan is certainly an option, but one that many people would feel is an unworthy tradeoff with what they'd have to give up.
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The difference with smoking vs the other things mentioned frequently in this thread (beyond likelihood of addiction), is that the reductions in lifespan with smoking are huge.
The average smoker loses at least a decade of their expected lifespan from what I can see.
Alcohol's effect on expected lifespan is more disputed, but even those claiming it's a negative in all quantities, generally make far smaller claims as to the degree of reduction for moderate/average use than are the case for smoking.
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Additionally, the average smoker doesn't appear to even be particularly fond of their activity. I do not meet many middle aged smokers that talk in any sort of particularly positive terms about their smoking or that seem to have positive memories associated with it.