Mostly bench rest shooters with very solid rest. You can't hold 1/8th moa in the field and probably in field target shooting. My experience anyway. Nothing wrong with 1/8th moa turrets though.
I love 1/8 on the bench. All depends on what range you are shooting and the size of your targets. If you are shooting tiny stuff (tooth pick), you want to be able to adjust as fine as possible. Beyond that, it is just more clicks most of the time.