
Just looking at the article, it seems the parents will be especially targeted if their children are caught multiple times, in public, drinking. That sounds entirely reasonable.
As to the broader topic, I think parents should decide when it's ok for children to have small amounts of alcohol (not to the point of intoxication). A 13 year old being allowed to have a small glass of red wine with Thanksgiving dinner is an entirely different matter than a 13 year old being allowed to get "smashed" at home, at will.
As a parent myself, I would have no objection to my kids having a very occassional glass of wine with a special meal once they'd gotten to be 15 or so. At no time at all would I allow my children to consume alcohol in excess while they live in my home.
Minimum legal drinking age of 21 can protect against later risk of death
The minimum legal drinking age (MLDA) in the U.S. Regulates the age at which individuals can legally purchase and possess alcohol in public. An MLDA of 21 has been linked to a number of benefits, including a lower risk for alcoholism in adulthood. However, no studies have examined linkages between exposure to MLDAs during young adulthood and mortality later in life. This study examined if young adults - college and non-college students - exposed to a permissive MLDA (Younger than 21) had a higher risk of death from alcohol-related chronic diseases compared to those exposed to an MLDA of 21. Ref. Source 1i.