I don't think it's absolutely certain that already produced cp is inherently and irredeemably harmful after the fact. It has been debated and researched but it's not really clear if distribution and consumption should be treated with anywhere near the same criminality as production. Also parent brings up a good point that almost all platforms that allow content sharing deal with pretty massive amounts of things like cp, but we as a society never really address the popularity head on, similar to how we have treated drug abuse historically ("it's something bad that only bad people do and there aren't that many of them--certainly none I know!")