Big LOL, as I've had that same feeling about more posts than I can count over the years.  Usually if someone writes something that is so patently idiotic that it convinces me I will never want to waste another nanosecond reading another serving of tripe by the same author, I hit the ignore button so fast my fingers produce little sonic booms.

But this idea has been brought up before and has been either ignored or rejected by Theymos.  In fact, I seem to recall someone calling for a demerit function shortly after the introduction of the merit system.  So as much as I sympathize with your frustration and support your suggestion, I'd keep my expectations low if I were you.