Very good point! Had never thought of that as being a filter. How many Type II civilizations, having exhausted the resources of their home system, can take the next big step?
To them, it may not be such an enormous leap, being perhaps millions of years more technologically advanced than we are. But to us, it seems almost insurmountable, and may actually be the greatest Great Filter of all.
Exactly. And that next big step of getting out of the star system also depends on being able to find a planet that can support your type of life. Sure, there's plenty of Earth-like planets out there, in their stars' habitable zones. But how many of those have sufficient water? Oxygen? Sufficient magnetic field to protect the planet from their Suns? Rotate fast enough to not cook one side while the other freezes? Finding such a planet means locating tons of options, and potentially sending drones (I doubt even much more advanced civs would be able to tell that much about a planet from light-years away) to them to find maybe one that has an actual liveable climate. That would take many years. This is all before trying to send people.
On a side note, here's a somewhat-related story I found years ago that you might find interesting:
THE ROAD NOT TAKEN - Harry Turtledove