Suppose that you ask a question, and field some answers.
After reading them, you then unexpectedly realize that your question admits only trivial answers, due to some edge case you didn't realize you had to exclude when you wrote it.
It is useful that people have shown you this, but now you want to exclude the edge case and try again.
What's the right thing to do here? You've already gotten answers, and those people deserve upvotes and etc. Do you make a new question that's a variant of the old one, and try again? Do you edit your existing question?
For example, this just happened to me herehere. I asked about commutative operations distributing over both multiplication and addition. Since I didn't leave out the possibility that the operation be undefined at the multiplicative identity, the only such operations are trivial. But there may be highly interesting, non-trivial operations which blow up to infinity as one operand approaches 1, for example. Do I make a second question and ask this now?