Just to make it abundantly clear: Under normal circumstances, I would think that this is absolutely not acceptable and this would be a reason for rollback and possibly locking the question, given further attempts of completely changing the meaning of the question.
Nevertheless, I think there are two aspects at work that make this a special case:
The edits are working in a similar direction in both carving out non-subjective and merely historical aspects and omitting things making it too broad. Basically, it is not a back and forth between different approaches on what the question should actually ask (so-called edit-wars). And it kind of preserves one aspect of the original question that has originally been present.
The author of the question has uttered his approval regarding the content of the question after the major edits by Chris as preserving the gist of what he actually wanted to ask. This happened in now-deleted comments, which makes it impossible to be understood by other users. This is quite unfortunate and I guess this question would not have been asked if they would still be there. They also seem to be honestly thankful.
I have to admit that before looking at the timeline in detail, I felt the same way. I even shared the skepticism regarding the honesty of the questions, as opposed to mere trolling. One could uphold this skepticism reading the comments, but this would have to be based on quite hard sarcasm/cynism, which cannot be easily identified in written text sometimes. Therefore, I will have to conclude in dubio pro reo for now.