Yes it is true. They don't make an impression when I don't see it.
Call me old fashioned, but I have hands. I physically put my phone away because I do not want to watch the screen on my phone when the screen is showing an ad instead of showing what I wanted to see.
Companies are paying Google to show me ads that I don't see.
Coca Cola's brand recognition does not come from YouTube ads. It comes from signs in the real world, visual merchandising in stores and product placement in shows.