TBH what often happens to folk particularly when younger is that alcohol is of course legal, relatively easy to get (even with age controls) and to some extent usually more socially acceptable to consume in public – if you are for instance part of a group of youths in some “favourite hanging out place” and aren’t blatantly acting like twats; a passer by is less likely to call the cops on you than if you are furtively smoking something.
Even smoking tobacco attracts scrutiny as it increasingly has to be done outside of a licensed venue or even at house parties (many people live in rented houses or don’t want to pollute their interior décor) whereas alcohol can normally always be consumed inside.
not sure what its like for todays teens but in the 80s it was not uncommon to go out with a wider group of friends who were mostly drinkers and tobacco smokers – only a smaller subset of the group were stoners and particularly towards the end of a night when the pubs had shut (in England this was and sometimes still is as early as 23:00) would break off from the wider group to smoke.
Thus people are often quite drunk before they might start to smoke cannabis and it is not surprising they subsequently feel ill. As tryptameanie said they would have got equally ill had they carried on drinking.
In social settings outside of licensed premises where users are not put under pressure to cram their use of any one substance into a certain time frame and/or are more mature and know their limits this is going to be less of an issue.
