This has been my experience as well. Even at the d3 level. Some coaches simply think they are smarter than everyone else. It rarely works and often hurts their own team more than it helps.In order for this to be at thing you need a pitcher that can hit their spots 70% of the time AND you need a hitter that can receive and act on the information. Outside of the top levels of P5 schools this is a moot point. Certainly will not matter in HS or Travel Ball. The main benefit of this exercise is to get into the heads of the pitchers, coaches, and parents. As you can see from the responses in this thread in the context of getting in someones head it is pretty successful.
Ken Eriksen used to play these type of stupid games every time my DD pitched against USF. He would stand at 3rd and try and pick her grip and tell the hitter what he thought she was going to throw. Near end of her last game against them her Senior year, she looked over at at him and asked if he finnally figured out that she used the same grip for every pitch. He was not amused.
Returning to the title of the thread. Relaying pitch location from 2nd base is extremely common at the college level. A lot of high school teams in our area also try to do it but when 90% of the pitches called are to the outside, why bother.