There are so many practical problems with doing such a thing. The first is that it's incredibly economically expensive to do so. If the aliens aren't spending t

There are so many practical problems with doing such a thing. The first is that it's incredibly economically expensive to do so. If the aliens aren't spending their resources, whose resources are they spending? Clearly it must be theirs. Secondly, the thought of unleashing a civilization-destroying self-replicating AI into the galaxy is so dangerous that I doubt any civilization would do it. Imagine the dangers of that. All it takes is for the AI to misidentify you as "another" civilization and wipe you out, or for these AI to be taken over by another party and turned against you, or for the AI to actually just misidentify you and kill you. The dangers of that far outweigh the benefits in the miniscule chance that the Dark Forest is in fact real.