It could be for another, entirely different reason.
If you look at our history, from the development of radio communication to now, you'll see that our massive, high power broadcasting of radio signals into space has only been occurring for 125 years or so.
It is not only likely, but entirely probable that such radio signals will cease coming from our planet as we switch over to light based communications, and tightbands beamed source to source. The radio broadcast spectrum will continue to go down in power so that more spectrum can be used without interference. After all, if your signal can't be heard a mile away, someone a mile away can also use the same frequency.
If our societal use of high power broadcast signal lasts 200 years before we go dark, that is a VERY narrow cosmic time slice to catch a whiff of another society. It's entirely possible that 5 minutes before the first radio tower pointed towards the sky and turned on the receiver that the last broadcast signal of an alien civilization floated past our planet.
Finally, there is also the point that maybe a society doesn't WANT to be heard. Lights attract insects, maybe there are insects out there we don't want to attract.