I think that the biggest issue's gonna be a time gap.

Life shows up and spends a long time doing not much, then exponential growth kicks in, life gets smart and suicides out in 100000 years or so.

The rate of intelligent and communicating planets is going to be low enough; the chance of two such planets within a distance that allowed for bidirectional communication existing simultaneously is dwindling - and even then they'll be at different points in their growth curves.

If ever we meet aliens they'll be cavemen or gods.