It was a high end thing, first produced by makers such as Egg. 1790s though 1830s there was a great deal of competition and patton fever. There was a flint lock that changed the angle of the flint every time you cocked your gun, and platinum touch hole liners, or gold flash pan.
There was a cartoon done about1790 that showed a ‘gun that can kill in every direction’ the shooter shot and missed a grouse, but managed to kill his dog, his friend, his bat man.
Rollers were an extra feature, a sign of a fine gun.
When you hold your finger on a frizzen and flick it open very slowly, with the roller it moves smooth. With out a roller you can feel it drag. It’s not a chatter but very slow you notice it not as smooth.
It’s slight.
I’ve had several locks with rollers by L&R and Davis. I can’t say one worked better then an unrolled. My best lock is on my Centermark and it’s a Davis. However my Siler work real well.