Yep, I would agree that it would be very unlikely that a civilization capable of launching them, WOULD launch them. We are nowhere close to being able to build these probes ourselves, but already understand the dangers of doing so. Even assuming that VN probes WERE launched by some civs, who is to say that they aren't stopped by other even more advanced civs before they can become a problem?

Overall, my feeling is that there are 2 things which cause the 'dead' universe we see.

1. The Great Filter is the evolution of intelligence. Since we are here, its easy for us to assume the evolution of sentience is normal, but the dinosaurs were around for almost 200m years and got nowhere. And if not for a string of lucky events, we wouldn't even be here, wondering these things right now.

2. Advanced civilizations prefer simulation and dont need to colonize the universe at all, I think this would be even more likely if the first point is true, since once you understand the physics of the universe, see that its a cold dead place and you are bound by its physical laws, simulation has a lot more to offer. I would love to invent my own universes, simulate them, and be able to watch and manipulate them with omnipotence.