Resonances in a room are even more of a problem with live sound as the venue owners don't like us modifying their buildings. Instead we use graphic equalisers to tame the response of the system at points coincident with the room's resonance points creating an overall flat response.
When you see someone using a graphic as a tone control, or worse, with a smiley face curve, it is not being used correctly.
What? You mean the stereotypical (groan!!) gull wing curve shape applied to EQ sliders doesn't work for all rooms in all situations? Oh Shoot!