It's both isn't it. It has to be. Have you ever been to a wedding or convention that is serving? Alcohol absolutely is a social lubricant
By your definition ecstasy is a social drug or any drug at a rave is social (Note I have never seen MDMA turn anti-social).
In my experience most drugs are “social” - the heroin users I knew were a tight crowd! Weed is definitely social for those that partake.
Serve cocaine, MDMA and meth at a wedding and everybody will have a social blast too.
I’m genuinely curious how you define sociability of a drug or substance. I know alcohol is detrimental to society at large. On an individual basis, I find it quite attractive for social gatherings.
Alcohol is deeply socially destructive - we know the stereotypical examples of damage in the the poor and the indigenous communities. The examples of damage in middle-class homes of the wealthy (e.g. doctors) and the average working class (tradies and nurses) is much less visible.
The words “social” and “alcohol” are immiscible.
I have an alcohol free home (I have seen too many friends slowly change from one small drink a night to a problem within a few years.
I have seen too many devastating consequences of “social” drinking to think it is safe. Of course we all mostly do unsafe things regularly!