That would seem logical that a wider seat would be more susceptible to tears. We don't get any complaints of torn covers though. In my experience, the handlebars and side panels make contact with the ground. We don't even have scuffs on our own personal seats. This photo captured from my helmet cam kind of paints a picture. My bags are certainly holding the bike up and if there were a large sharp object where the seat is, I might have had a torn cover. Since our seats aren't extremely hard, the foam does give to pressure from all angles, which will allow the vinyl to flex as well. A better example might be the DR350 and KLX650c we have here that have had the same cover on for a full decade now, and they have definitely been down. Busted mirrors, busted turn signals, scuffed tanks/shrouds, scratched engine covers, among other uglies, but no torn seat. Maybe all of our customers are superb riders and don't tip over like myself, who knows.
I can tell you, riding around on a stock seat is not worth the fear of a potential increase in cover damage.
And if you're wondering what happened in the photo, my attempt at a climbing a rock shelf was unsuccessful. Fail.