[scott_ni]

On the other hand, requiring reputation could incentivize spamming and worthless posts. For example, if you already have an automated voting bot, why not make it upvote your new bot accounts to transfer "rep" and allow more upvotes?

[fabian2k]

That is one of the things I meant by "more obvious patterns". That works of course, but you also create connections in the other direction now as well for your vote fraud.

There is another effect that probably doesn't apply to Reddit, but on Stack Overflow it can be pretty noticeable if you upvote crappy posts by your socks too much, and someone will investigate.