It is however a tool to be used with caution for the newbee who can use the Karma (in combination with the number of posts) to get an idea of how thrust worthy the info by a member is.
For instance: if 1 member with Karma 1 states it is A and 3 members with Karma 20+ say is is not A; I would know what to believe.
Maybe I'm just being overoptimistic, but I usually feel like I can tell "good" responses from "bad" ones by just reading them in context, and possibly looking at a few other of either author's posts (and yes, the number of posts is relevant).
But I agree that used with caution, as you suggest, karma could be helpful to some.