Or we ourselves are a filter, destroying any form of intelligent life that could do anything different before it can evolve so, before our own self-destruction. Maybe we have already done it and we do not even know it.
Or, civilizations have become so advanced they mastered higher dimensional movement and are now occupying positions in time and space that we cannot see, and no matter where we hide they can always see us without being detected.
Organisms competing with other organisms is what has created intelligent life. I think more of that competition would only lead to even more intelligent life.
