People make edits for lots of reasons. Anyone claiming that people only make edits for only one reason is wrong, no matter what one reason they claim.
- Spelling & grammar.
- Corrections someone brought up further down the thread (see below)
- Adding links or correcting URLs of links, especially when parentheses are involved.
- Adding details that you didn't think of earlier.
- Rephrasing something after realizing it was unintentionally offensive.
- Rephrasing something after realizing it was just plain rude.
- Redacting the entire comment in protest.
- Rephrasing something after realizing that it was the sort of rambling and vaguely incoherent long & convoluted sentence that readers are likely to eventually get tired of reading, because it's really just that obnoxious even if people used to write like this all the time in the 18th century or earlier eras of literary compositional history.
- ~~Spelling & grammar.~~ Fixing markup!
- Removing duplicate redundancy that says the same thing twice and should be deduplicated.