I can see that. But again, it gets to at what point an alien civ is at technologically, or whether there would even be a technological frame of reference. As 'tout says, we find broadcast to be entirely useful . . . and if we ever get to the point where the benefits of broadcast are outweighed by the inherent power loss, we’re pretty damned close to our overall power limits.
Hell, if we want to take it to extremes, we might as well assume that the reason we’ve detected no EM is because all 3764 alien civilizations have built Dyson spheres.
The reason we’ve never been contact is probably much simpler.
Space is very, very, very very, very big. Almost beyond our capabilities to imagine so. And we are equally small and insignificant. So it’s far more likely that we’ve simply never been noticed, than been purposely excluded.
And it’s also possible that whatever life is out there is just as isolated as we are.