I saw an article where parents' justification for spanking was "It worked for me" ergo, I'll spank my kids or won't spank my kids because that's what I experienced. Look at all the things that "worked fine" for you: No helmets, no seatbelts, mothers who smoked and drank when they were pregnant. No one's posting on Facebook in favor of those gems.
The problem with "it worked fine for me," is that parents made those choices because they literally didn't know better. They worked with the best knowledge they had at the time. But now we know. We have research and experience and the evening news to show us what happened to the old way of thinking. And thank goodness. Our children will know more than we do -- let's hope!
There is too much easily accessible information for us to claim ignorance or not even try to find out if the old way is still the best way. I think parents' greatest fear isn't in doing something new, it's in doing something imperfectly. If we haven't seen it done another way, how will we be effective? Luckily, parenting comes with a lot of leeway. It's OK to parent imperfectly as long as your intentions are good and you pay attention to whether what you're doing works and adjust accordingly. Our children will live through our imperfections -- after all, many of us of a certain age lived through lawn darts and secondhand smoke and we turned out just fine! Who knows what our children will look back on and shake their heads. "Hey," we'll say "We didn't know any better!"