There are a number of minor reasons why this behaviour is detrimental, and so it should be discouraged.
In rough order of importance:
We generally discourage changes that affect the previous efforts of people who have answered the question. If the changes to a question make an answer no longer applicable, or worse, a magnet for downvotes, it is unfair on the answerer.
This is only applicable where answers exist.
Any votes on the question are no longer up-to-date, and risk sending the wrong impression about the value of the question to the community.
This even applies to downvotes, as a downvote costs the voter reputation when the question is undeleted.
Yes, the voters may change their votes after an edit, but they may not revisit the question and notice their opinion on the question has changed.
This is only applicable where votes have been applied.
The feedback comments that triggered the deletion will still exist, and will be confusing to new readers of the question. Obsolete comments have a tendency to trigger hostile replies from confused late-comers.
This is only applicable where comments have been made.
Stack Exchange automatically monitors the quality of contributions of users, and brings suspected issues to the attention of moderations - for example, when a new user is having trouble understanding the scope of the site, and frequently has their questions closed or deleted. It gives us an opportunity to contact them with assistance.
This behaviour will likely circumvent such systems.
Stack Exchange keeps statistics on the number of questions opened, closed, deleted, etc. so we can see how the site is doing. Shenanigans like this will add noise to those figures.
For these reasons, this behaviour should be discouraged.
If it is immediately noticed, the question should be rolled-back and deleted, and the questioner should be encouraged to cut-and-paste the version they like into a new question.
However, if significant voting has occurred and an answer has been written before the problem is noticed, it is too late; the damage that would be caused by deleting the question outweighs these minor reasons. It should be left as is, and the questioner warned in a comment against repeating this behaviour.