"X can't be that difficult to implement": something one probably shouldn't say about an open source project unless one is about to give it a go themselves.
By writing that captcha was implemented because it was easy to implement, you suggest that easy-to-implement property has nontrivial explanatory power. I disagree, since I believe this property also holds for other alternatives, so can't explain the choice, and shouldn't be used as an argument. It's just a matter of rationalist nitpicking.
(It's more difficult for me, because I don't know the project (or python, for that matter), but must be trivial for people who do. In any case, the intended meaning, as applied to Karma limit, is the same as with captcha in the sentence that originated the exchange, so it refers to how difficult it would be to implement the Karma limit (instead) for the person who implemented captcha.)
I accept your criticism and will stop nitpicking. What we did was particularly "easy" because we only turned that captcha on and styled it. Captcha-on-submit was already there in the Reddit code.
We'll try something else to reduce the impact of spam soon.
Spam (curiously enough, always for jewelry) accounts for maybe two-thirds of what comes through the LW Discussion area's RSS feed these days. So although the moderators have been doing a great job of quickly removing it from the site itself, it remains a substantial annoyance for those of us who keep track of LW through a feed.
I think it's time to revisit the possibility of making it harder for people to post in the discussion area. Clearly it would suffice to limit posting privileges to those who have a positive karma balance. If that seems too draconian, as it did to some people in the previous thread, it would probably be enough to limit posting privileges to those who have ever received a single upvote on any comment they have ever posted.
Would any administrator care to undertake this? If so, many thanks.
(My apologies if an unfinished version of this post briefly appeared on the site some hours ago.)