Do you have any evidence that the average advertiser can "clearly see" how this is calculated? Try this: Go to any Facebook Ads group, DM 10 advertisers and ask them if the "Impression" metric tracks accounts or people. See what % of them reply confused.
Second, it appears that you haven't ran Facebook Ads at all. When you see your ad set performance, one of the primary columns you see is "Reach". If you hover over, you'll see this:
> Reach > The number of people who saw your ads at least once. Reach is different to impressions, which may include multiple views of your ads by the same people.
My argument is that Facebook is changing the definition of "people" to "accounts". If you are the SAME ad both on Facebook and Instagram, Facebook will report your reach as "2" (compared to "1", as it was before the change). How is this "noise about nothing"?
Third, the documentation you linked me to has been recently updated to reflect the news release Facebook announced. This information hasn't always been there.
Your arguments made sense at the beginning (with regards to the "double pricing" argument) but they appear extremely biased now.