TLIK
“Schmutz always existed, and it is ignorant and primitive to blame it on current developments. Yet, one can use technology the wrong ways and for the wrong reasons.”
While I certainly agree with you that the blame on FB was overstated as a “prime reason”..
However, I don’t think your comparison to the past is correct; Once-upon-a time, for order for one to get a hold of “Schmutz” he really had to go out of the way, whereas, nowadays, he/she can just be innocently “surfing” Facebook” accounts and fall into the worst imagined. It certainly does not help in any imperfect (but still solvable) marriage.
Many of the secular world can certainly attest to that, how FB ruined their marriage. I am not saying you should or shouldn’t be using it, but you certainly have to be on the alert and use it sparingly, carefully and, mainly halachically