That's pretty much it. I've seen how market mechanisms and natural consequences don't necessarily lead to my kids making sound decisions. Before having kids I envisioned myself being a Laissez-faire parent. Now my wife tells me that I need to calm down and be less authoritarian.
Same experience. Everyone is a libertarian until they meet kids and realize how impressionable and gullible even the smartest of them are at a young age -- easy prey for the advertising industry, the junk food industry, the junk media industry, and worse. Giving them total freedom at too young an age doesn't really help them be free, it helps them be slaves to someone else with more ad dollars.
Libertarianism and freedom, etc, rest upon a foundation of a well educated society with members who have enough understanding of themselves and their world to resist exploitative influences -- you are not born ready for freedom, in fact, you are born literally a baby, totally dependent for years. After years of good parenting which helps you develop self respect, values, and critical thinking, hopefully then you are ready to responsibly embrace that freedom.
Moreover, how much my perspective was changed made me realize some problems in today's society could have to do with the fact that being a parent or at least being around and being responsible for kids, was a universal fact of life for nearly all adults until very recently, but now it's possible for a young adult to barely ever encounter a child through their entire 20s and beyond. No wonder it's easy to end up with a worldview that does not account for how children can fit into it.
Not everyone is a libertarian at any point in their lives; not all of us needed to have children to realize that people (and not just ones under whichever age of majority you subscribe to) are shaped by the systems they live in. But I ask, what about those who are unable to "responsibly embrace that freedom"? What is to be done about them?
"I was a libertarian until I had children" is very funny.