It does not show an account's voting strength as a function of its stake.

It doesn't show it directly, but indirectly there is a similar effect because the most powerful accounts always "live" on the right side of the curve (they themselves can put a post there, so the only question becomes how far out to the right it goes) and the least powerful move between the right and left depending on the actions of the most powerful (in a sense this could be viewed as another way the most powerful have even more power).

Flattening the curve on posts flattens the power imbalance between accounts as one of its effects (or at least no longer amplifies it)