You’re right, overindulgence of pornography can be harmful, but overindulgence of anything can be harmful. You imply that checks and balances are needed, but what would those be? Should we limit peoples’ ability to watch porn? Where would this interference stop? Do we limit peoples’ ability to eat, to ensure that they don’t hurt themselves?
Perhaps people would be more open to getting help for their addictions if the subject of their addiction were less taboo.