I do remember looking at some Investor Day materials where they mentioned average spend, and balance carrying percentages.
I remember that 40% of Double Cash accounts carry interest bearing balances, while only 10% of Prestige accounts do.
Makes Prestige look more sort of like a charge card.
Perhaps when they were designing the offering they got some of the assumptions wrong (projecting more balances on their top end cards) which is why its been the constant drib/drab of benny cuts on Prestige.
Amex has mostly learned to live without the benefits of collecting interest, although they are certainly trying to change that over the years.