I just realise that people still can edit questions after it has been answered. I think it makes no sense.
Take a usual forum / board for example. Most of the large forums forbid to edit even your own post after few minutes.
Simply because people want to know in what context other replies were made exactly.
This site has information which is even more sensitive. The answers must be technically precise.
However it is easily possible to edit question to be something completely different (maliciously or by accident through several changes from different users).
In prospective of time this will lead to broken answers. Old game of chinese whispers basically.
Here the example (imaginery chain of edits made in different time by different people reading it differently):
"Did you hear that Isaac won 2 millions in lottery" "Isaac won large amount of money in gambling" "A person got lucky in horse betting" "Dirty money for dirty people" "Unidentified subject shot in dark alley. Mafia at suspect"
I do understand that if you lose articles or mistype words it looks bad. However this must be done during the question has been answered. If the answerer was OK with the text then we should keep it frozen once the OP marked it as Answered.