Generally on SE sites there are rules about not significantly changing a question after it has been answered. This is a problem because it can invalidate the answers.
This question on Meta is highly downvoted but if you read the answers, you'll see the general consensus is:
Editing the question in a way that invalidates answers or changes the meaning of the question is strongly discouraged. It is allowed for questions that would otherwise be closed, but generally such disruptive edits will be quickly rolled back by other users.
To that end, I flagged a recent question for moderator attention because I felt the edit was inappropriate. I thought that this was the case because:
- It added a third, different example to the question and asked whether that third example was grammatical or not.
- The question had already received five answers.
- The change was not made by the OP of the question.
I'll grant that it didn't necessarily "invalidate" the answers but it did make the answers look incomplete as they were essentially ignoring one of the examples unless they had inadvertently discussed that example previously.
I made the personal choice not to roll back the edit myself because I was not sure I was correct, though my comment about the heavy-handedness of the edit was upvoted and the person who made the edit posted rude comments directed to myself and another user who agreed with me which were subsequently deleted (thanks). After the personal attack, I chose not to roll back because I didn't want to get into an edit war about it, and opted to wait for moderator response.
The response I received was mixed and confusing.
My flag was marked as helpful but no change was made to the question to revert it to the previous version.