I'm only a student pilot, and recently during a group ground school lesson the instructor mentioned that it is against the FARs to give a "courtesy call" to ATC as you are not speaking your full intentions upon first communication.

For example, say there are multiple aircraft attempting to talk to Ground at a very busy airport. It appears relatively common (and maybe smart?) to simply call in "Anytown Ground, Skyhawk 1234A" and wait for a response instead of going forward with your entire spiel and canceling out another transmission.

Is this an example of real world versus the legal world?

Thanks