@GeneJ has attached a comment to the question now called Determining what old document with Illegible handwriting says? that reflects a concern that the process of iterative editing of a question and original answer (by different people) can move them in different directions.
That has the potential to create the situation where an old answer looks at best inadequate and perhaps nonsensical when viewed by an (inexperienced) user unaware of the practice. They might well ask "Why was such a poor response voted up by these experts?"
As careful researchers, a casual user might always compare the timestamps of the Q and the A, and if there is a mismatch review the edit trail of both to find the point(s) where they were contemperaneous, and then decide if the information is what is needed. Or he or she might look for a source with a more rational organisation.
I can envisage a circumstance in which I would edit my previous answer back to a stub in order to remove the potential for embarrassment. From a community perspective, that is not desirable.