I think it's more 'as an adult I realise that what I faced as a teenager was not all it appeared to be'.
Every cohort of teenagers since ancient times has believed, it seems, that their parents didn't understand. I think then one finds the ignorance was usually balanced in the other direction. Parents in general do want their offspring to grow to be self sufficient, which does require some pain - we're not going to be here forever to care for our kids - but most parents want their kids to get through their whole life with fulfillment and happiness. Sometimes that means a little hardship for a greater life overall.
This I think accounts for parents, in general, seeming to be hard on teenagers. Those teenagers will either realise it was for good or initiate a revolution in how they treat their own teens. That revolution hasn't happened yet.
My observation is that we go in cycles - parents are liberal, their children are more conservative (when they become parents), so their children respond by being more liberal, etc..