@isobel
If we define "immoral" as "harmful to everyone involved" - it doesn't seem contradictory to me.

There are links to referenced scientific papers on the bottom of the pages usually (attached screenshot).
I have not read and analysed all of them (I did read a few of them years ago when I first learned about this site).

My experience aligns with what is written there though.

[Disclosure] I am a former porn addict (with some lasting health issues). Currently clean & married.