Solid roller lifters

In simple terms that make sence.
but at 7500 rpm, that rocker arm is beating the crap out of the valve stem, and the cam is doing the same thing to the roller lifter.
7500 times a minute compared to to 800-1200 time a minute.
Is there just not enough oil flinging around for proper lube at idle? Maybe the reason for pressure feed rollers on the lifter???