Who’s being uncritical here? I’m not an alcoholic and neither is my sister. That doesn’t mean alcoholism doesn’t exist nor that there aren’t very real harms to a small subset of the population. Great enough harm (that also impacts on non-alcoholics), that we’ve collectively decided to regulate an otherwise legal substance. Would you suggest that we shouldn’t age-limit alcohol? And even with the things you quote - driving and gun ownership - there’s still an age limit, not no age limit. The specific number is irrelevant and up for discussion, but we’ve still decided for those things that there exists a “too young” category.

EDITED to remove a stupid phone autocorrection/autoinsertion.