No, commits can be co-authored. And the committer and author don’t even need to be the same! But the point, as I read it, is: what matters is the context, i.e

No, commits can be co-authored. And the committer and author don’t even need to be the same! But the point, as I read it, is: what matters is the context, i.e. if a line is faulty, how did things look like when it wasn’t faulty? The commit’s content is more often more important than the committer, although the committer is useful because you can ask them if they’re still around.