Heck, you can't - to the best of my knowledge - even comment on changes in a commit instead of just the sum total of changes in a pull request. It's as if GitHub expects everyone to use squash on merge workflows, which is insane for developers who know how to structure commits and write commit messages. Oh yeah, and you can't comment on commit messages neither. In Gerrit (which otherwise has plenty of problems, too), they show up as part of the patch.