Sounds like you have been a good friend and have made some excellent suggestions.  That may be all you can do with respect to other people's children.
You don't mention if you have a child in that age range.  If you do, I could see concern that your rule could be challenged if your child's friends are allowed to have a Facebook page.  If that is the case be sure to have ongoing conversations with your child about the reasons behind the age rule.

Hi there,

This is such a great question and one that we're all going to have to answer for ourselves as kids get more and more access to technology. I think every parent has to figure out what's best for their kids and their family. I don't know that "minding your own business" is the right approach...I think it's great that you care enough to have these tough conversations with your friends. But I think once you've shared your opinions, and the information you've drawn from to form those opinions, you have to respect the parents' decision and trust that they're doing what they think is best for their children.

A lot of experts are actually saying that "forbidding" the use of Facebook and other tools and technologies might be a big mistake. If a kid wants to get on Facebook, they're going to get on Facebook. Between the library, their friends' houses, and the many other public access points, it's naive for a parent to think they can keep their kids away. It may be healthier to sit with your child as they set up their Facebook page so that you can talk to them about the choices they make about what to share and the possible consequences of those decisions today and in the future. If you start having open dialog from the start, you'll be more likely to stay in the "circle of trust" rather than having a kid who's living a secret life online that you know nothing about.

A mom I trush a lot recently said this to me.  "Is it scary to think about your middle schooler going to a dance?  Yes!  But do you forbid them from going?  No!  But do you drop them off at the dance without talking to them about appropriate behavior there?  No!  Nor do you pick them up from the dance without talking to them about what happened there.  Taking care of your kids online isn't so different.  You can't tell them they can't go, but you also don't drop them off their without talking to them first and you don't miss the chance to talk to them after."  That made a lot of sense to me!

Education.com has a great resource about raising kids in the digital world. Maybe some of those articles would be helpful for you to share with your friends and to check out yourself. There really aren't easy answers when it comes to this issue. I think it's important that we all keep talking about it, do the best we can for our kids, and try to support other parents as they do the same.

Best,
Kat