ATC here. It's not always because someone is grumpy or for formal discipline.

I only gave a Brasher Warning one time, only because my trainer told me to. I suppose it depends on the culture/facility, but where I learned it, they had more of the attitude that it was to have an informal conversation to find out what happened and what the pilot and/or controller can do differently next time.

After my supervisor talked with the pilot and listened to the tapes, we discovered that my control instruction was ambiguous and that I should be more clear next time (and the pilot should follow the minimum altitudes on the approach plate).