My biggest pet peeve of “decks” is how there are people who will bang out a deck and use that skill to “own a meeting” or “own a strategy”. To me that is like the person that tries to take over a meeting by commanding a whiteboard. A deck is not a plan and should not be treated by one, even if the story it tells seems to work.
The biggest thing about writing down strategic choices is that they serve to build a corporate history (over a year or two, not really thinking about decades). Why decisions are made is rather important because companies, like people, can make the same mistakes over time without history.
For example, it is likely that people are treating 6 page memos as “goals” unto themselves. Managers are likely evaluating employees on the memos as much as the results. And of course, you won’t find a lot of successful employees who can’t memo. This is not negative about Amazon, but literally every process becomes corrupt this way.