The Search for Extraterrestrial Intelligence, or SETI, is a speculative venture. There is currently zero evidence for the existence of extraterrestrial life, let alone intelligent extraterrestrial life - why the heck are we bothering to search for life forms advanced enough to blast radio waves into space? As speculative as this hunt may be, it is based on sound science methodology and, should the slightest hint of alien intelligence be detected, it would transform our understanding about our place in this grand cosmic sandbox.
Listening to random stars in the hope that one may play host to a transmitting alien civilization is beyond speculative, however - given enough time and computational power, yes, it only ever has a low probability of success. But say if we know that a given star plays host to a planet, not too dissimilar to Earth, orbiting within a magical distance from its host star that is just the right temperature for liquid water to exist on its rocky surface? Wouldn't it make sense to aim our radio telescopes at those star systems?