When I led a team of 6 people, I did the opposite. The guideline was to always use the imperative form if you knew there was a better way, especially if there's a precedent or it's a written rule in a guideline, but even for opinionated things.
It resulted in clear debate in PRs, ZERO personal conflicts, everything was very civil and productive.
I'm just mentioning this as a personal anecdote, not suggesting that there's a right or wrong way. The reason this worked in my team is because we were, and still are - a team. They're still doing it like that even though I'm no longer involved in day to day.