Who are you?

I am in the process of beefing up my software skills (Logic Pro X, nothing to do with presentations), and am spending a lot of time watching screen shot movies. I am just wondering why in these training sessions, the face of the presenter is not shown? OK, the screen real estate needs to be as big as possible, and a constant “talking head” on your screen distracts, but maybe a small introduction, at the beginning of a lesson?

This could be an idea for presentations that are used in cold email approaches: put a very short, very short, intro video of yourself on page 1 (to keep file size emailable and not take away the attention from the slides that follow).