If I might jump in, this exactly true, and because of the addictive nature and need to for ever more intense 'imagery/fantasy' to achieve the same level of interst/stimulation in the sexually and morally 'numbed' receiver, the porn gets worse, the user gets more depraved (even if hidden), and it all spirals down.
The reverse can be acheived, but it is an uphill battle when porn is so pervasive and seemingly too few people perceive it's corrosive effects on society.
Like other corruptive influences, the bad effects will be obvious to us long after the damage has been done. A little like the Catholic Church, which allowed active homosexuality to flourish in seminaries and dioceses, and then ended up with priests (in Boston) promoting man/boy sex and then with raped and molested teenage boys all over the country.