My headcanon is that the maneuver was just a lot harder to accomplish than it's depicted. Distance from other ships, residual shield levels, etc. allow it to be possible but unlikely. They threw in a line in episode 9 that it was 1/million (kind of like the Death Star kill shot). I think it makes the Holdo character more interesting if she has some sort of force intuition or just advanced analytical/risk-taking skills to actually pull it off.