Earlier quoted context omitted.
When you use the word "extremely", what kind of incidence are you referring to? If someone says "water is extremely common in the solar system", I'd expect maybe two in three planets to have it. Half at minimum.
More than half of divorce cases in the US mention compulsive pornography usage: https://s3.amazonaws.com/thf_media/2010/pdf/ManningTST.pdf
Makes me think about gambling. Most people either don't do any or do it in normal proportions. For those that do have trouble, as this argument is about addiction after all, there's a self-imposed timeout mechanism that gets centrally registered so that any gambling place will enforce the timeout on this person. I don't know how much it helps, and it also goes into having to identify users to avoid circumventing even a self-imposed safeguard, but it might be an industry to compare against and draw research from (I haven't seen it mentioned yet in the greater thread).