The original Kickstarter had a Stretch Goal (that was never met) that included a 4-5 player rule variant. Did anything ever come out of that?
The plan was that if we hit that, Henry would lock me in a room until I came out with something decent. For better or worse, that never happened.
For a good part the game's lifespan, it scaled down to 3 players. At some point I bumped it up to 7, since I would consider other games better to play in the 3-6 player range; and if I'd rather play 5-player Resistance myself, who am I to suggest anyone play 5-player WH?
There were a few days where I sat down and tried to make 6 player setups work better, but couldn't make it work without reworking it into a different game. Games that lost after one mislynch felt awful, and all the setups that were still interesting to play were heavily Witch-biased.
I think WH is a very different and much better game with 9+ players than 7-8, and it would be a similarly different (and similarly worse) game with 6 or less.