The problem is one of those evolutionary arms races, for a reason in your observation: if the points are useful in seeing the popularity of a given post or comment, then why not simply create a bunch of fake accounts to boost said post/comment (which is exactly what the OP was complaining about in the first place).
Individual karma ratings allow a weighting for upvotes so that, in theory, contributors who have a track record of constructive interaction can be the ones who have more influence on what rises to algorithmic prominence. But, of course, everything can be gamed, hence upvoting bot/sock puppet-rings like the one OP observed, or people buying accounts on reddit that had pre-established karma to let them astroturf away with impunity.
No idea what the long-term solution is, beyond the vague "build a community of known faces/names" which runs the opposite risk of turning cliquish or closed-off to new content. Or maybe abolishing all algorithms and just sorting everything by new (which brings us back to the ancient commenting issue of a whole chain of people saying "first!" rather than adding any meaningful observations).