I am not sure it is even a question of competency. I think it is a question of motivation. It is the same reason why Twitter doesn't crack down on their bots. Both sites have an inherit interest in appearing popular. Having 50k upvotes or 50m followers looks more impressive than 25k and 25m. It is possible that those companies feel the value of those increased numbers is greater than the potential damage bots do to the community. HN doesn't have the same motivation since HN is more of a vanity project with a bigger focus on the good of the community.

Good point. I would insert "short-term" here... because I doubt it's any these corps long-term interests.

On the other hand, Digg died because they were effectively letting publishers buy front-page slots ahead of organic submissions. If Reddit becomes known for manipulation, it could also suffer (though its scale, heterogeneity and skepticism of shilling are significant antibodies).

I wonder if that was in their TOS when they themselves were initially writing comments under various handles to appear more popular :p

Reddit's core value seems to be "the end justifies the means."

Reddit or SV in general or YC too.