67% done with War and Peace

Nabakov complained that War and Peace was filled with too many coincidences, and I’m sure he was referring to the scene where after Andrei is injured he sees Kuragin next to him with his leg amputated. But why can’t this happen? Life has so many more, seemingly impossible coincidences that why can’t it happen in fiction? Tolstoy covers the entire range of human experience, including coincidence (providence?).