Depends who you ask. If you’re talking strictly size, plenty of bodybuilders saw better back growth after dropping deads. Other guys use deads but don’t “count it” as part of their back training. We discussed a bunch about it in this thread.
Just sayin’, deads are a big basic exercise, without a doubt, but they’re not “essential” for back size. If you want to train the back without stressing the lower back and legs, deadlift variations don’t fit the bill 100% because they’ll always use the low back/legs to some extent.