It is probable that emitting electromagnetic waves as a method of communication will be a short-lived phenomenon as an advanced society creates some other, better method...possible something quantum in nature?
So all the civilizations scattered throughout the universe would emit such radiation in short one-time bursts.
We are probably not listening properly.
Listening to these far away stars for electronic signatures would be like going back in our history to 1M years ago a making the conjecture that there is no life here.
We are looking at data points that are millions of years old by the earlies count. So not really relevant to what may be out there today. Maybe life started there at the same time that it did here. They will discover us millions of years from now.