Several things have been pointed out.
Powerful broadcast signals probably have a very short window. Powerful broadcast is already fading here, after less than 100 years, as more efficient carefully directed low power beams and cable based networks take over.
Some entities may feel that trying to call attention to themselves in an unknown universe may not be a wise thing to do, and others may be far more interested in their yoga classes.
Significant evolution depends entirely on sexual reproduction. How likely it is for primitive microbes to develop the joys of sex is totally unknown, but this single factor could greatly reduce the possibility of intelligent life in the universe.
Some entities may feel that trying to call attention to themselves in an unknown universe may not be a wise thing to do, and others may be far more interested in their yoga classes.
Significant evolution depends entirely on sexual reproduction. How likely it is for primitive microbes to develop the joys of sex is totally unknown, but this single factor could greatly reduce the possibility of intelligent life in the universe.