There's two different things going on here: the short-term and the long-term. Here's an example:
(note: the following has exaggeration for effect; live with it)
ESLguy comes in and posts something like:
"we go store Yesterday n bi meets" rite iz ?
teecher sez rong but i rite i no.
- Answer #1 says no, that's wrong.
- Answer #2 says no, and here's a better way to say it.
- Answer #3 says, "itZ Go0d 2 mEe."
- Answer #4 says no, and here are the particular language/grammar rules you're breaking.
Unsurprisingly, ESLguy prefers answer #3, and accepts it as the best. Oops.
For a variety of reasons, people wander into the site and run across the question. Over the next few years, answers 2 and 4 get a bunch of up votes and 3 gets even more down votes.
End result (?)
The theory is that, in the long run, answers 2 & 4 will have accumulated scores that are so much higher than the accepted answer that it will be obvious to all that—while neither is the accepted answer—they are plainly better answers.