They aren't required to watch them, but the voters do all get screeners. They at least have the opportunity to watch it, regardless of whether they've seen it i

They aren't required to watch them, but the voters do all get screeners. They at least have the opportunity to watch it, regardless of whether they've seen it in the theater. They don't vote just for what they've heard of. The Academy has a reputation for seeking "artistic merit" even at a cost of good entertainment. They're hoping to advance something that didn't do well at the box office. Sometimes that means giving awards to films that turn out to be dogs, but sometimes they manage to promote things that deserve attention. A lot of Oscar-bait gets a small release at the end of the year, to qualify it for the Oscars. If it gets a nomination, they'll use that as part of a wider campaign later. That's why they send out screeners: they know that many members won't have had a chance to see it in the theater.