Specifically, it seems that it lubricates one's ability to utilize the vocabulary one has already learned more fluently (possibly by removing some anxiety/inhibitions?). I believe it was not suggested to have an effect on comprehension.
Perhaps this can translate to programming languages as well to some extent?
Getting smashed really does help, I've had great nights drinking with dudes who don't speak a word of English. I've always put this down to lowered inhibition.
I've never felt my comprehension, grammar or vocab improved, just that my conversation partners and I were committed to getting hammered together, and persisting was the focus of the evening's entertainment for all concerned.
In a sober situation, you're much more likely to give up.
Despite their excellent reading ability, I feel like what really separates them and someone with high fluency is simply being willing to practice their spoken. I'm sure alcohol could help someone overcome that.