There are different ways to respond to a document that contains typos.
Sometimes, we don’t see the typos at all.
Other times, we see them but don’t seem to register them consciously. This can subtly influence how we feel about the document, the subject, or the author.
The typos may assert themselves into our consciousness and distract us. Maybe we grow annoyed or find ourselves becoming judgmental.
Or we may see the typos as a natural consequence of an author creating with bold strokes, not bogging down. Suggesting fixes in this case may not be a form of criticism, but a way to begin participating. Whether or not the author changes the document in response to the suggestions is less important than whether or not the feeling of participating starts to develop.