Krugger said: no one has fought Rinnosuke and a battle is the best sign of affection in Gensokyo noticed enemies are now allies
This makes sense for this. No one has battled more times than Marisa and Reimu in canon, so this could explain things. Also, Marisa is manlier than Rinnosuke, anyway.
There's a human population in Gensokyo. Do the math. Yup, we have men. Or do you dare say Unzan is unmanly to his face?
We not interested in mere nameless human men. We need at least named ones. And with some haxpower, that required using spellcard system or some awesome ability for mundane utility.