I asked a question that got four upvotes. But one person had various complaints about it. I thought it was fine but invited her (him?) to improve it. The result was in my opinion of no use to anyone, and has since got one downvote. No one had an answer before the edit, and the edit made it impossible to answer. But since people have posted related discussion as answers, it cannot be deleted.
(Not sure if I am reading the rep history correctly, but it looks like four up, none down before and one down, none up after. How do airlines calculate the cost of a Brompton?)
Seems that it defeats the purpose of rep-points to delete them on the original poster (OP) of a question if the original was good and someone has edited it to be worse. Conversely, adding them to an OP who asks a terrible question when the value of the question comes from a competent editor.
Same principle applies to good and bad edited answers.
BUT, if the edit is trivial (spelling errors, grammar, etc.) then the content is obviously still from the OP. I think it is probably impossible for AI to decide when to "shift the blame."