Roto Grips Facebook page posted a review of the No Rules Pearl and in the Facebook comments, I noticed multiple posts along the lines of "but good luck making a 10 pin with it."  I laughed to myself because I've never had to switch balls to shoot spares. I was always taught to flatten my release and throw it straight.

But it had me wondering. Is that a lost art among bowlers?  Are people not taught to shoot spares like that anymore? Is it all just throwing a plastic with your normal release and letting it skate through all conditions now?

Personally I always found it beneficial to just throw whatever ball I'm using flat so I never had to waste a bag spot on a plastic ball.

I've never really heard about it damaging equipment or anything. Is it a common issue? What actually happens?

Any time a ball goes into the gutter there's a higher risk of damage - gouges and scratches particularly.  The faster the ball is thrown the higher the risk.  --  JohnP

+1 mainzer I also use urethane as well, will never use reactive equipment EVER, Stuff is too expensive in the first place, but again to each his own.