Can or should something be done about the gross incorrectness of this accepted answer?
I've made an edit to it (without I think destroying the spirit of the answer). See if that's better.
IMHO it had the spirit right, just had a couple of (admittedly important) details wrong.
Generally what I see done is that a competing answer is written. If it gets more votes than the accepted answer, that tends to stick out.
In case you didn't realize, mods have no power over the checkmark. That's entirely up to the questioner. That's something to keep in mind when you're reading any answer on a StackExchange site. This is why its not uncommon to see questions where a highly-voted answer right under the "accepted" one seems way better than the accepted one.
In short, always read the second answer. :-)