In order for someone on another planet to be detectable by us humans with our present tech they would have to broadcast radio signals. We developed this tech a little over a century ago. And as a civilization we had plenty of opportunities to self destruct, from nuclear and biological warfare, to destroying the environment. We also have the chance of developing a "better than radio" communication method that's completely obscure to us at this point.
The window of of that civilization being detectable is squarely between them developing radio and them dying off or using some tech that we cannot discern as artificial signals. The window for us detecting them has been ~50 years so far. Given the size of the galaxy and the minuteness of that window overlap it's pretty clear the chances of communication are slim. And indeed even if we do detect something, calling it communication might really be pushing our definition of that.
