It originally worked the way you describe

The great curse of blockchain code is that when it was ever used, it needs to be present forever. That however presents opportunity to "turn back time" and actually use it. For this reason I have full confidence that it never worked in described way.
_{In the process I've learned that manabars used to hold basis points instead of power values like they do today (up to HF20) - strange thing.}
The rules of voting were vastly different but that aspect remains the same. Consecutive votes drop in power right of the bat like today, but it is even worse - due to lesser precision of basis points you can actually stop all mana regeneration by voting too frequently.