At least if you want to be a credited writer. Sure you might get a story by here or there, but don’t bet on any written by’s before your name anytime soon without knowing editing. And by editing I mean film editing. Script editing is a given. But film editing is the best way of staying in sync with everyone beyond your agent or manager who are gonna take your side anyway. Producers, Directors, Execs all are about the final cut. And if you’re writing War & Peace, enjoy the paycheck because someone name Lindelof or Black or Rosenberg, etc is gonna be molding your epic into a lean-mean-runs-under-two-hours-so-it-can-run-six-times-a-day machine.
By the way, War & Peace never makes it past a page flip by the reader anyway.