Planetary collisions happen all the time. All of Mercury, Venus, Earth, and Mars in our solar system had them. We can see their signatures in other solar system

Planetary collisions happen all the time. All of Mercury, Venus, Earth, and Mars in our solar system had them. We can see their signatures in other solar systems too: see https://en.wikipedia.org/wiki/List_of_extrasolar_planetary_collisions https://en.wikipedia.org/wiki/List_of_extrasolar_planetary_c... Whatever the great filter is, it's not planetary-scale collisions during the accretion phase of solar system formation.