With or without spacers, the steering wheels are turning to the same angle, that's all I'm saying. I can't see why it would have an impact on steering radius. Without knowing much about the spindles myself, there is a reason for the bigger steering stops. Maybe it is to prevent rubbing on a certain component with stock wheels? Depending on the wheel offset, it could
be possible to grind them down. I'm not telling you to go do it, just saying that it could be a reason.
Scrub radius means that, as the wheel center is pushed further away from the pivot point (ball joints), the tire moves forward and back more as you turn the wheel. You can read some of the effects here, and why a bigger scrub radius (as in running spacers) will negatively affect handling. Scrub radius - Wikipedia, the free encyclopedia