They're not saying teenage binge drinking is never problematic – they actually used the words "risks of hurting ourselves is probably higher than the reward".
The point is that youths do risky things; it's a normal part of growing up, and is how you learn about risk and responsibility. Youth binge drinking shouldn't be seen as separate from youths just doing risky things because that's what youths do, else you'll come up with "solutions" that don't address the real issue and fail to solve anything at all.
It's fair enough to say that someone who parties a lot in their early twenties, but doesn't hurt anyone else or themselves too seriously, then grows out of it and lives an upstanding life is not a major problem, whereas someone who continues to drink excessively and destructively when they're older and needing to be responsible is a problem.
And sure, they're somewhat related, but not so much so that they should be considered one and the same, when the underlying causes are usually very different.