Unlimited Points leads to strange abuses. Creating scarcity minimized abuse, and increased the chance that people would use them up. Otherwise 1% of users create 99% of the moderations, and it only takes 1 bad apple to ruin the pie. YMMV!
This is more or less how the Slashdot tagging system works, but more advanced than how the moderation system works. But still, abstracts in patent filings are generally oversimplifications.