The point of a whiteboard interview for me isn't about accuracy and efficiency. It's about seeing whether the person can code and can talk to me about coding.
Yes, of course. I rely on compilers, linters, and editor syntax highlighting when writing code, so it'd be pretty hypocritical for me to penalize people who can't access those things. People can sketch out a pretty messy pseudo-code implementation if they want, and then we'll just spend the rest of the interview cleaning it up, making it correct, extending it, talking about quirks of their implementation.