Or matter?
Is extending parental dependency the problem? If someone starts college at 20 instead of 18 they are likely at home longer. But a lot of people aren't leaving home for college anyway, or they return home after college whether they graduate or not.
If a bunch of kids start high school at 16 instead of 14 is it going to cause serious problems? It seems to me the only issues would be those that we create by our own expectations.
How would a potential employer know they were graduating college at 24 vs 22, and without knowing the reason for the difference why would they care. "I'm afraid we can't hire you at FAANG, it seems you had to repeat the first grade 15 years ago."
A FAANG probably wouldn't care either way, but a Fortune 500 might, and numerous other places of employment might also pick the person that graduated "on time" if most other things are equal between two candidates.
_If_ they knew the reason it might matter less, but not all employers will take the time to figure out what the reason was, and not all reasons are necessarily something you'd want to share and offer up freely because it might be very personal. They'd have to trust the reason given as well. A person that graduated on time presents no such hassle, or unknowns.
I'm not saying it is correct to do this, it's just what I _imagine_ is likely to happen given how people tend to sometimes judge people on other inconsequential stuff.
Are the metrics:
1. Based on university entrance (in which case you need to recourse and ask the same questions of that) or
2. Based on some pragmatic list of things that will help the child become a good part of society or
3. Completely arbitrary.