> 1. It's a good indicator of how much you know for simple problems.
Google doesn't solve simple problems.
> 2. You can practice.
Maybe if the interviewee was still in college they could "practice" coding on a whiteboard, but considering they may have other obligations like family and work they probably won't have time to practice such a pointless skill.
Personally, I wouldn't need to practice in the first place as I interview extremely well and could easily code on a whiteboard, I just find it antiquated and pointless to do so which was the reason for my comment - not because I am bad at it.