How does the 5 minute rule encourage auto voting?

The 5 minute window is a "reverse auction." It's meant to somewhat discourage auto voting. Any votes made on a post in the first five minutes lose part of their curation rewards. I'm not sure if it's exactly linear... but as an example, let's assume you were the only person to vote on a post and your vote is worth .20

If you vote at 5 minutes, you get a .10 curation reward. If you vote at 1 minute you get a .02 cent curation reward and .08 is returned back to the broader rewards pool.

It doesn’t help auto voting... in fact it keeps auto voters from all voting immediately as a post is published. Instead voters “bid” (thus the reverse auction) by voting earlier than the five minutes, gambling that the curation reward percent they are foregoing, will be less than the increase they’ll see from voters coming in after them.

The 5 minute rule is not the culprit in encouraging auto voting. It’s a mitigating factor. The mechanic where early voters earn a percentage of subsequent voters curation rewards is the root of auto votes.