I think it would be a mistake to do so. It can potentially create confusion for future readers, and I don't believe it would provide enough benefit to outweigh potential drawbacks of backlash from some post authors.
Questions are asked at a specific point in time (visible on each question), and are answered at a point in time after that. Editing the tense ...
Some had terrible answers and had positive scores still. Not to offend
anyone. Those accounts seem dead.
I think for this particular negative aspect of the questions you are referring to, the normal way is to downvote these answers if they are clearly not accurate. The downvote button's tooltip suggests this:
This answer is not useful
Of course, if the ...