It would be a stretch to blame MM for the popularity in shed hunting. But I think the reason that shed hunting is becoming so popular is the same reason that many of us come to MM, bragging. When I find a great shed or a nice set, I love to show it off (we all do) and I love to see what other guys have found. All the braggin' gets people interested, who wouldn't want to find some sweet sheds. I remember clearly, when I was 11 years old, a guy showed off a fresh 350" set, and at that moment I knew I wanted to hunt horns.
Anymore, I'm really careful who I show off my sheds to, especially my collection of "keepers". People see them and many have decided to take up shed hunting on the spot (and of course asked me where I found all of mine) Most people have a treasure hunting streak, and when you see the "treasure" that others have found, you want in (like the gold rushes) We can't blame Monster Muleys or any other site. Realistically, if we've ever shown off any of our finds, we've got to blame ourselves.