I clicked the link to read the article but could not see all 18, points of her rules.
Anyway, one thing I have to add is this:
many kids have phones. That means they have a cell phone number to "their" phone. Kids, NO matter what age, DO give our their phone numbers to others who ask. That could be, other kids no matter what age, AND also adults/other parents etc. And this, can be dangerous. Because, the parents will not know necessarily, "who" has their child's phone number. And then the ripple effect of kids giving out their phone number is: that the kids who they gave their phone number to... CAN ALSO give out your child's phone number to others who your child may not even know... and who your child does not know nor like. And that can mean, others who have your child's phone number, can be either nice or bully types. And then, "prank calls" can occur etc. I see this myself, amongst my daughter's classmates. And it has happened.
So for ME... "our" rule (although my kids do not have cell phones, but we have cell phones as parents) is that: AT NO TIME, can our kids give out "our" phone numbers to ANYONE, unless... they ask us first, if it is okay.
And my kids DO follow this "rule." We are open and honest and blunt with them, about the ramifications of others having our phone number.
THUS, our phone numbers... are PRIVATE. WE DECIDE, who to give our phone numbers, to. The same rule goes for our e-mail addresses.
This is a very important thing, to consider, with kids.
And, when/if I do allow our kids to give our phone number to others, no matter who that may be... *I* tell that person myself, that at no time, can they give our phone number to ANYONE else, without my... permission. I make this clear, to my kids' friends and to their parents. And I have never had a problem with that.
I make it clear, that our phone number is private.