Is it though? We know the tiers are not straight from Europe Universalis or Crusader Kings. There aren't just three, but
at least four (city-state, principality, kingdom, empire) and Wiz was just like "And so on, etc." about them. It seems just as reasonable to conclude that the base Prestige of an Empire is
60. Granted, we have no idea how much Prussia and Ottoman's actually have Prestige, so maybe they're neck-and-neck and ten extra would shift them around. But that's a complete assumption.
Also, not-final numbers. If you want to base conclusions on them, alright then,
but the whole point of the giant WIP sticker on the screenshots is to point out that the numbers will change. (Actually, nevermind, it seems they've noticed how the WIP sticker did nothing to prevent in-depth arguments about the numbers and no longer put that there.

)
WILL. Wiz even explicitly said as much in the comments, the formula for calculating these is getting reworked. They've laid out their design idea that the base Prestige should not account for much. If the design idea and screenshots contradict each other, it seems more logical to assume that the numbers
will shift than to expect them to be set in stone.