Certainly. As my colleagues have mentioned, 21% of 15- to 19-year-olds are using. If you set that age higher, at 21 or 25, you're forcing those young people to continue to go to the illegal market to obtain their product. It's not like they are going to stop. Complete prohibition hasn't stopped them. An age limitation is not going to stop them either.
Interestingly, partially we see such high rates of cannabis use in this country because our work around minimum drinking ages has been so successful. Also, there are limits on legal outlets for alcohol sales. In many parts of this country, especially in rural areas, it is much easier to get cannabis than it is to get alcohol. In fact, the cannabis comes right to your school.
Setting that age, despite the neurological evidence that may support it, is in effect going to continue the harms for those young people.