Actually that is a good point. I've known alchies who could drink all day and not get drunk or impaired.
What is your point?
there are many that get just blasted off of one drink too...usually late stage alcoholic's
its like there are stages in the life of a daily drinker... in the beginning they can get impaired with a normal amount of drinks.
then on the the ever increasing tolerance level, where the amount of drinks becomes obscene at some point.
then they level off into a "perma drunk" by having a daily maintenance usage. or dosage ...where amounts start to mean less and less.... until thru the body breaking down from years of abuse they will only require one or two drinks to appear to be fully impaired.
Any connection between alcohol and cannabis is a stretch....since there is zero to compare..... where usually the drinker will be the one who tries to make the ties to cannabis,,, in order to show the harms,,,, since their substance of choice has many years in a row been way up towards the top, on the list of substances people party with and their harm index....