What's contested is if its the porn itself that causes the addiction or the feedback loop and easy access is what leads to compulsive consumption. No mainstream psychological organization is saying that there are no addictive or compulsive behaviors associated with excess porn consuption, just that it doesnt meet the critia as a medically diagnosed addiction and is closer to a compulsion.
For laymen however, referring to it as an addiction is what most accurately encompasses its impact on those who become compulsive consumers of it.