(Personal opinion below, and does not necessarily represent the views of chess.com management or anyone else with authority or insight.)
There's no doubt that a harsher consequence for fair play violations would reduce the symptoms you see, but it also has the concomitant effect of creating a huge debris pile of players going off the deep end in protest, some of whom are simply struggling with their newness to the site, to chess, and to the desired etiquette suggested by fair play.
Finding the right middleground is the trick ... and not an easy one to pull off. Give it more time while you reserve judgment, I'd suggest.
I have had very bad luck the last week or so with players who either abandon a lost position, or who stall for 15 minutes in between turns in a lost position with hopes that I'm not paying attention any longer when they move, and therefore they can win on time. I am wondering if anyone else has a similar experience in the last week or two; and if it's related to the fair play policy being softened to an offender can not play for 5 minutes. When the punishment for violating the fair play policy was that someone couldn't accept open challenges until rehabbing their play with friends..it seemed like the sportsmanship was better on the site.