You are not experienced with handling guns, are you?
The analogy to guns is applicable to ANY SAFETY DEVICE. Safeties are designed to provide additional protection in the case of an accident. To depend on a safety for everyday protection without practicing safe operation is foolish, and the way that many accidents happen. Just like *** handling accidents.
You're assuming that:
#1 the thin decal/adhesive label chainstay protector is thick enough and tough enough to protect against chain rub under pressure, and/or when the chain sags down and makes contact with the chainstay, and that it
#2 covers the chainstay all the way back to the dropout and to the inside where the chain will rub if there is inadequate clearance because of the small cog.
My Treks are earlier models, and I can tell you that the Trek supplied chainstay protector/covers do not provide coverage all the way to the dropout, and will not protect the chainstay against anything more than the lightest droop or contact with the chain, and they do tear and wear away.
That's a lot of assuming, considering that if you're wrong at all, the result is a ruined carbon frame (that Trek is not going to replace under warranty).