People tend to mix up the terms editing and proofreading and although some aspects overlap, there's an actual difference.
While editing: - you look at inconsistencies/unclear parts - you check facts - you optimize phraseology/flow/quality/tone of voice
While with proofreading the writing is already good, you only need to take out punctuation/grammar/spelling/language/typing errors.
So with that being said, proofreading doesn't improve terrible writing BUT it does please a grammer junkie!
Some people find inspiration in eating their friends and their dogs. Others find inspiration in eating, their friends and their dogs. Punctuation saves lives!