Then there really is no need to even have merge commits. But, as far as I know, there no way to disable the creation of a merge commit when using the merge butt

Then there really is no need to even have merge commits. But, as far as I know, there no way to disable the creation of a merge commit when using the merge button on the github PR page. The one thing you lose with just making one PR per commit is the relationship between a set of commits used to implement a feature. One commit involves some retractoring to make it easier to cleanly implement the feature. The other commit would be the feature and tests, and the last commit would be to add calls/references to that feature. If these commits were kept in the same branch and merged in a single PR, then it would be easy to see the relation between them. If they were merged as 3 separate PRs, then it would be more difficult to see why the refactoring was done, especially if PRs for unrelated changes were merged in the interim.