It was originally invented to incentivise manual curation. It was envisaged that hundreds or thousands of engaged users would be finding good posts and those that voted early got bigger curation rewards when the larger accounts voted after. It gamified it also.
Then they changed it down to 5 and after that I didn't have a clue wat it was for.
Hundreds or thousands, now that is a dream I would love to be realised! Yes, I remember 30 mins, everyone stayed away until 30 minutes and 1 second.
It was kinda ridiculous, the tense wait till that time to see if you actually got any votes. ha