There are so many other factors that can affect accuracy besides just which gas system the rifle uses. There are plenty of piston rifles that are more accurate than many DI rifles; however, that's in spite of - not because of - the gas system.
I'm talking about the same rifle—changing between the two systems. I never said that generally one system was better than the other, I'm giving an example where the piston driven system was.
Very aware of what can and can't effect a rifle's accuracy in general terms.