> Now a developer who is working on a new feature is reluctant to take opportunities to refactor incase their commit message doesn't match the "standard".

Having maintained a few projects on Github, I routinely reject commits that both introduce new features and fix/refactor things. Refactoring is good, but jumping on a project and changing everything at once is a strong indicator of a lack of focus. The "fix some of everything" commits usually lack tests and documentation updates which wouldn't have been overlooked if the contributor took a step away and looked at the big picture.