Rewriting may sometimes change the meaning of the writer's content.
That is why it should be done in a more concentrated manner.
You can recognize many good writers from the way their text reads alone.
That's because they've already found their voice, making their writing distinct from most everything else on the market.
This unique "flavor" is something that a good editor will try to keep when they go and edit any specific piece of writing.
And doing that is never easy.
When a piece merely requires a small amount of changes, such as a few grammar corrections a good writing software can spot, then altering the author's voice isn't that much of an issue.
Since any revisions you make is minimal, the updates aren't likely to affect the work's individuality one bit.
Problems start, however, when the piece requires a considerable amount of changes.
Some situations where this will happen include:

• When the facts of the piece have been verified to be wrong.
  
• When the writing style doesn't conform to the publication guidelines.
  
• When certain passages are not clear enough to be easily understood by the publication's audience.
  

The worst situation is when you read through a piece and come away with the feeling that something's wrong, even though you couldn't pinpoint the exact reason for it.
In such a case, you may need to rewrite a huge chunk of text over numerous areas.
Polishing the work, all while retaining the original writer's voice, can turn out very difficult in such a situation.