I'm pretty sure that this didn't occur before, but I could be misremembering.
A question already has several replies.
If I reply to the original question, I can see the entire thread while writing my reply. If I then decide to edit my reply, I only see the original question.
If I reply to someone else's reply, again I can see the entire thread. If I edit, then I only see that reply (that I replied to), not the entire thread.