I disagree with this. I dont know of a top 30 US guild that doesnt use WeakAuras EXTENSIVELY. I've been in several top 30 guilds and every one of them used literally hundreds of WeakAuras for things from When to get away from people/the raid all the way to CD rotations.
That means that it's effective and probably convenient, but that's not the same thing as being necessary. It might possibly be necessary to have something that does those things, but as kenn9530 says there are other options.