I had the same initial reaction, but then again...doing it during the meeting, always, ensures that all participants are at least talking about the same thing. I’ve been in meetings where it doesn’t become clear until very late that someone is bullshitting and has not actually read the materials, or read them so lightly that their comments/opinions are not well directed. This is, imho, much worse than making sure everyone is on the same page. Since everyone is presumably going to need to read the docs at some point anyway, incorporating the activity doesn’t really seem like a waste of time to me.
I've been writing software professionally for about 20 years. I'm not sure I've ever been to a meeting where most of the attendees have prepared by reading relevant materials including documents attached to the meeting invite. Because of this experience, I have a very different expectation. I attach documents to the meeting invite so that people can know where to find it for reference during but mostly after the meeting.
Sometimes there is no clear or a weak "chair". Furthermore, if the bullshitter is influential enough that you don't have time/capital in-meeting to call their BS? That's why BS is successful.
I see the Amazon approach as an augment to the chair to keep the discussion on-topic. If it's not discussed on the paper, the burden is on the dissenter to provide info / present credentials to rebut.
This process is designed to ensure that the docs have been read and have been freshly read. I think of it as moving the time and effort into a defined and nearby time, and it's far from a "waste" of time, IMO.
Only somewhat related here, but we recently did a QP where our team came in without previously breaking epics into smaller tasks.
One argument is that we could've done that outside of the meeting, in its own meeting. But that actually wouldn't have saved any time, but would've probably cost more. Basically, we set aside the afternoon to accomplish the task at hand. If we had broke it into multiple days, there would've been memory debt we'd have to refresh.
As an engineer, I feel that requiring pre-homework for a meeting can be detrimental. As other posters mentioned, going through it all together in the scheduled meeting ensures that everyone is on the page. Additionally, it means that an hour long meeting doesn't actually require an hour and a half of my time, so I can better judge and plan my schedule.
Amazon is also big on "mechanisms over good intentions".
Asking everyone to please do these actions before the meeting is a good intention. Everyone wants to, but you know things happen and well I skimmed it but I didn't really have time and now I'm going to ask questions that page 2 answers clearly because I didn't read it. Everyone's time is wasted.
Forcing everyone to spend 15 minutes right now is a mechanism. It's much more effective.