I do not think the second half of your statement is true. Certainly there was drug use in hunter/gatherer societies but it was mostly shamanistic/ritualistic use, not 'stress relief'. The example that you give of alcohol only really came on the scene with the advent of farming, which remains a small fraction of the history of humankind.
So you’re potentially correct, though we don’t know if fermentation was used earlier, either intentionally or opportunistically.
Can we really say this?
Are we sure that finding a patch of 'those' mushrooms wouldn't have just meant party time?
We know that (for instance) animals seem to seek them out...
This paper  supports my characterisation of being mostly for shamanistic/ritualistic use.
And this paper  suggests that drug use also had medicinal benefits. But that is from a modern hunter-gatherer society that has undoubtedly been influenced by outside societies (indeed the drug they smoke has been imported from another continent), so I'm not sure how indicative of pre-historic hunter-gatherer use it is.
Where I remain dubious is the assertion that drugs have always been used for 'stress relief'. My feeling is that stress - as we understand it - was not something much experienced by hunter-gatherer societies.