Amazon’s practice is a reaction to the fact that nobody actually does this. According to the article I read about this years ago, they realized that “creating a strong culture around reading before the meeting” also isn’t possible because many attendees had a meeting before this one, and couldn’t prepare for that meeting because they had a meeting before that, etc.
On paper you could punch a ton of holes in this: Why not reduce the number of meetings people have to attend? Doesn’t the reading reduce the amount of time available in the meeting to actually make decisions? But it would seem that in practice they found that the meetings people were attending did in fact have value, and that even with the reading time a lot of decisions got made.
So this may just be one of those things where you have to look at the results instead of worrying about what could theoretically be done differently. And it sounds like people really like the results and that the benefits of this approach outweigh the drawbacks, at least at Amazon.