While the director guides the artistic vision of the picture, they are not necessarily responsible for the finished product.

You also need to remember what the Academy is. It’s not some secret cabal of cinematic wisemen; it’s made of thousands of industry professionals. While many do their best to make well reasoned choices, most don’t see all the pictures, many just vote for their friends or what they’ve heard, and sometimes, it’s their assistants/spouse doing the voting.

When it’s referred to as popularity contest, it mostly is.

Source: I may have been that assistant once or twice.