Our eyes are at the top of our body and humans are generally tall (standing up). You look forward and then look down naturally.
We generally read top down because of this. We generally want the bulk of information at the same level as our eyes. It's why tv's aren't on the ground.
I feel like many are overthinking this.
Up-and-coming.
Top-of-the-line.
I could go on, but I don't want to get you down.