You don't have to study. I never studied and I passed some whiteboard interviews and have a steady job. Sure, higher paying jobs (such as at Google) might have more difficult interviews which require some study but at less competitive companies you can do fine if you have a decent background in logic and problem solving.

Also, I have to agree with the other commenter here that it could be way worse if professional credentialing starts to be required. Then you have to shell out big money and deal with way more bullshit requirements than just whether you can write code on a whiteboard (e.g. boring classes, standardized tests, diversity quotas, etc.)