I met Mark many years ago at a Smart Marriages conference. I really like him.
I think he makes some good points on the porn avoidance.
Abstinence before marriage used to be quite important for social reasons. The way society was structured, a woman lost almost all value on the marriage market (her main - and often only - source of financial security), children born outside of wedlock were highly stigmatized, and child paternity was primarily determined by marriage. Abstinence before marriage is now primarily a religious issue. If that's important to someone, they will do it. If not, they won't.