The "Dark Forest" is fine for a scary sci-fi series, but it has many flaws that make it unrealistic as a real solution to the Fermi paradox.
Earth has been quite obviously life-bearing for at least 2 billion years. We should have been wiped out long ago.
The book series made up fantasy magic tech for how exactly a civilization can be destroyed by another without giving away their own location. I've yet to see an explanation for how that would be done in reality that doesn't give away the attacker's location.
It doesn't explain why nobody has colonized the galaxy.