The dark forest was one of the most popular Fermi solutions long before Liu's books, people just didn't refer to it by that name. Take a look at Fermi paradox Wikipedia article revision history.
I don't think Dark Forest is a good explanation, though. If you were one of the first space-faring civs and meant to avoid competition by striking younger civs preemptively, you could spread von Neumann probes all over the galaxy and either keep new civs at some technology level cap or destroy all the planets right away.
Also, there is no stealth in space, so you can just send a relativistic kill missile to any worlds where civs pop up, without having to step foot outside of your home system.
I don't think Dark Forest is a good explanation, though. If you were one of the first space-faring civs and meant to avoid competition by striking younger civs preemptively, you could spread von Neumann probes all over the galaxy and either keep new civs at some technology level cap or destroy all the planets right away.
Also, there is no stealth in space, so you can just send a relativistic kill missile to any worlds where civs pop up, without having to step foot outside of your home system.
Isaac Arthur has made many videos I like on these topics, but admittedly they are pretty long. E.g.: https://www.youtube.com/watch?v=LlhHE2VA1ic