I’m confident the Dark Forest Hypothesis is ONE reason why the universe is so quiet. The other is my Quantum Life Hypothesis, which posits that evolution is infinite, and has 3 main stages. Biological life, technological life, quantum life. In that order. Once biological life reaches a sufficiently advanced technological stage it either destroys itself or merges with technology, which likely makes it undetectable to our current technology. I think it’s a combination of these two hypotheses that explains why we haven’t heard anything. There are dangerous alien civilizations, and some or most are likely too highly advanced to be detected by our technology, whether they are deliberately quiet or not is pure speculation, but logic says survival errs on the side of caution.