I think honestly all the handwringing about why we can’t detect aliens may point to something else. Maybe the kinds of technology that would enable us to gather enough material to build Dyson spheres and escape the solar system simply are not feasible. If the best speed we can make is 75% of the speed of light, even the short distance to the nearest Star system becomes a generational journey. And getting up to that speed is going to take a lot of energy. As much as I love my space opera, I just don’t see it as a plausible future.

What seems possible is akin to the maximum ground speed on earth being limited to walking speed. At such a speed knowing about tribes a thousand miles away just isn’t going to happen, long distance communication makes no sense when the entire civilization might well be trapped in the nearest star system and maybe if super advanced, tge one next to theirs. They don’t need to broadcast anything beyond that, so they’re not going to develop it. What would we detect? Unless we somehow manage to detect them directly, there’s nothing to see, and nothing to hear.

The paradox seems to rest on the assumption of interstellar travel being feasible. If it’s not, Theres no paradox. They’re here, but too far away to hear or see.