That kid from third rock would not have dehumanized pornographers.

If he was watching pornography, the way he was at least some times he would have wondered what it was to date the woman.

Don Jon was watching pornography and being excessively promiscuous, engaging in sex addictions, to fuel his desire to change his physical appearance. That was really what he wanted and how he applying these sexual acts for motivation. But it left him unsatisfied.

I'm not saying it's healthy for all men to watch pornography, but all men are not Don Jon. He had a specific issue where things got real physical to motivate him for the gym, and he wasn't really satisfying his emotional or sexual needs. In comparison for example that kid from third rock didn't even go to the gym and we all have our own issues but the star of the movie was not the actor, all of his acts or the typical male in these situations... because then at least sometimes they would wonder about dating the woman or personality or something more than looks, but not as much if they were trying to get motivation to look like Don Jon...