To me, for the most part, the act of censoring and banning books is an individual matter. There are always exceptions, but for the population in general, I believe a person can make that decision on whether or not to read a book. I don't need some self-righteous person or group deciding for me.
In the marketplace of ideas, if word gets around that a book may be questionable for a certain age group, or the general populace, people will look at it a bit more closely to see if it deserves the label. And that's more democratic.
When my wife and I raised our two sons, we always had books in the house. While I can't think of any books being banned from our home, it certainly would have happened if there was something we didn't think was appropriate for them to read. That's not to say that they didn't read "controversial" books outside the home -- without our knowledge.
Hey, I did the same thing. Most folks I know hid books from their parents, and they all survived and became responsible citizens. For my generation, those books included "Lolita," "Candy," and "Peyton Place." After sneaking around to read them, most of us said, "What's the big deal?" I bet our parents, grandparents, and others in our distant past found racy magazines and pulp fiction to satisfy their curiosities about all sorts of things about the human condition.
Other books that titillated citizens through the years, and angered government and self-imposed censors, include "Madame Bovary," "Tropic of Cancer," "Brave New World," "Fanny Hill," "Naked Lunch," and "Howl." Wikipedia has a list of books banned by governments that you may find interesting.