Yes!
And you want them to learn in a situation where the stakes are lower: at 18, someone can put themselves into a ton of debt or put nudes in the wrong place and just nuke their life in a way that they can't fix for a decade and everyone shrugs and is like 'you're a grown up!'
Think of all the kids who back in the day got scammed out of their Neopoints, or lost all of their in game currency in GTA, etc. That's a way, way better way to learn about account security and who to trust than their first experience with scammers involving real money.
Is the problem that we're exploiting kids, or is the problem that we're exploiting people? We're not going to be able to protect kids from exploitation in a society/culture that explicitly condones exploitation. If we think exploiting people is fine, actually, as long as they're over 18, then your kids will never be safe, because they will grow up.
Even setting aside the obvious examples I listed, binge drinking used to be a huge problem amongst college aged kids. Who's to say that the Internet/social media wouldn't be similar? How many kids are going to flunk out of school because they can't stop watching digital crack and now mom and dad aren't around to stop them? And unlike binge drinking, your body won't eventually revolt against you, and with the addiction consultants The Machine employs, there will always be new content. People grow out of binge drinking because eventually it grows stale and hangovers when you're 35 are far worse than ones when you're 21, but that's not true of social media use.
To tie this to other issues, we're already seeing issues with relationship and family formation amongst young people. I'm not sure flash banging them with addictive content when they're in their prime years is the call. If all it took for the Internet to be healthy was holding off until adulthood, we'd expect people who were adults when they started to have a healthy relationship with social media. They very much do not.