Zero scrub can sometimes result in "zero feel". This pic shows typical rear drive scrub compared to typical front drive scrub. If you choose zero scrub, you may have to put in more toe to keep linkage tolerance reactions in check (for rear wheel drive). It can sometimes make for difficult steering decisions, when the front wheels are hunting different directions at the same time.
This happens because the true scrub radius is never constant, unless you run on a billiard table. If both are a little positive (while "pushing" the front wheels), you'll feel changes in surface drag and smoothness as true pull-feedback in the steering wheel.
This can be useful for the driver.
Regards, JimL