We always ask our candidates to write code in our interviews, but is there a reason why many companies seem to do this with pen & paper, or a blackboard? We si

We always ask our candidates to write code in our interviews, but is there a reason why many companies seem to do this with pen & paper, or a blackboard? We sit them in front of a computer with various editors/IDEs and ask them to code a function/class or two there on the machine. Isn't this better for the candidate (ie less stressful, interviews are stressful enough already) and more realistic, as they can use editor/IDE features and the compiler?