Annotation is one way to make citations explicit within the literature. So if there is a follow up paperer that says "we couldn't reproduce this part of the exp

Annotation is one way to make citations explicit within the literature. So if there is a follow up paperer that says "we couldn't reproduce this part of the experiment" it shows up in the original source. Similarly if there is an update to a method in the paper then the original method can be annotated. While this second case does look like editing you don't want to get rid of it because often you need to know what the original method was to interperet the results of that paper. Similarly community commentary on a work is not well supported by a purely editing model. Consider the Talmud for example, you have centuries of commentary and annotations on the Torah as a rather absurd end of the spectrum where editing the original work would be outright forbidden. I actually think that most of the difference comes down to what we name and what gets its own URI, but editing seems to imply that the changes become embedded in the original text whereas annotation is something that sits beside or on top of the text and is its own discrete document, a link rather than a commit so to speak.