Why Does Paper Cover Rock?

Rock, Paper, ScissorsThe Official Rock Paper Scissors Strategy Guide has basic rules to Rock Paper Scissors, along with an informative FAQ:

Does Rock crush Scissors or is Scissors dulled by Rock?
There is no clear answer to that question. Younger and aggressive (or American) players tend to favour the Rock crushing Scissors view. More liberal-minded players take the view that scissors are dulled by the Rock. The World RPS Society created a task force in 1987 with a hope of eventually resolving the issue but it has been locked in debate and we no longer hold much hope of quick resolution.

There are even tournaments.