In addition to the good points maelstrom makes, what frequency would you use? (Neither 121.5 nor 243 are acceptable answers)
In controlled airspace, each aircraft is supposed to be talking to a controller -- aircraft may overhear each other, but they don't chat amongst each other. It's important for the controller to control not only the air traffic, but also the radio traffic, to make sure communications aren't missed by having multiple stations transmitting simultaneously. Frequency congestion is often a serious problem in busy airspace.
The ATC facilities are designed to have good radio coverage for the airspace they control, but they often don't cover the ground very well, because of terrain issues. A drone pilot on the ground would typically have difficulty contacting or hearing ATC, so how is he going to know when a congested frequency is clear for him to talk to an aircraft flying overhead?
In uncontrolled airspace, airport traffic patterns generally have a designated frequency, but we should usually try to avoid traffic patterns. What frequency would you expect an aircraft outside of a traffic pattern to be using?
Do you have any idea what frequency the helicopter that was the original subject of this thread would have been required to listen to? Should have been listening to? Might have been listening to?