Someone should start a competing service then. My recommendation would be to have a "maximum karma" limit, at which point the account (mod or not) and all of its activity are deleted, and the owner has to sign up again and work their way back up from zero.
You get paid in power, money, fame, access ect for being president. Providing content for free to make someone else money doesn't have the same appeal that could tolerate term limits.
You'd lose any privileges associated with a high number of karma points, also all of your previous content would be removed, so people could cover the same territory in possibly new ways with less fear of being called redundant.
It basically compensates for first-mover advantage in forums.
As a thought experiment, your idea is interesting!
I see a few problems though. This wouldn't work for just any karma-based site. For example, on StackOverflow where there are good "canonical" answers to tech problems, and these get heavily upvoted (because they are useful), having them removed and later rephrased (possibly incorrectly) by a new user would be detrimental. So any system where "good" posts are archived and referenced wouldn't benefit from this.
Even when there are no canonical/permanent answers, the thought that every "good" post you make takes you nearer to account deletion is not exactly enticing. Why not simply get rid of points and make all posts ephemeral, kind of like Instagram stories? What good do points even do in a system where your account and posts will get inevitably deleted?
Also, wouldn't mediocre/bad accounts stick longer than "good" accounts, making the whole system worse? I don't mean terrible or troll accounts -- I understand the point system would still be used to ban or hide them -- but mediocre accounts which post mediocre/bad posts. Wouldn't they dominate in this kind of system?
If upvoting a post/comment (which gives the author karma points) would risk triggering its deletion (by making the author cross the karma threshold), then is that not effectively turning the karma system on its head?
Under such a system, if I think a post is valuable, I would then try to "protect" it and its author's account by downvoting it. Similarly, if I think a post is not valuable, I can help trigger its eventual deletion by upvoting it.
That would only really matter if the poster were really close to the threshold. Moreover the gaming of the system would be unlikely to work forever, requiring too much coordination of effort.
But to answer your question, yes, it is turning the karma system on its head for people near the top of the standings; the idea being that having "titans of karma" in the community becomes detrimental at some point.
I think deletion would be counterproductive, but maybe a karma limit after which you no longer accrue any points.
Say it's arbitrarily 1000 points (or whatever makes sense, as long as it's low enough it can be earned after a medium term of active contributing, but high enough very new users will have to learn the ropes of the community in order to reach it). After you reach this, people can tell you're a good contributor, but you can't earn any more points. Anything you do from that point cannot be done solely to earn points, removing that part of the "game".