Yes, the action of replacing a belt will sometimes be the demise of the tensioner. That's why my 300E has only the third belt in it's 280,000 mile life. I inspect the belt closely and often. It has yet to leave me beside the road. Luckily the belt is a much higher quality item than the tensioner.

As far as WHY they use a rubber bushing, I'm sure their thinking was for vibration and noise suppression. I'm not defending their design, I'm only stating why they chose this approach.

Have a great day,