LeBron is still taller than the average NBA player, and more to the point if he is being blitzed off a pick and roll, there is usually bound to be one short defender.

The point guards you listed are exceptional passers (first three have a claim to top 10 pg all time lists), and I’d argue Westbrook at 6’6" would have a better assist/turnover ratio than what he does now.

I don’t think Mitchell is a natural passer and that combined with his short stature limits his ability in this area. I think a good comp for Mitchell (in terms of passing ability) would be Kawhi. If Kawhi was closer to 6’ rather than his listed 6’7", I think his assists/to would be similar to Mitchell.

Also while wingspan in theory helps more with defense, I’d argue height is more important on offense as it allows you to see over opponents to make the right reads.