Well, that's outside of Gensokyo.
But the human village is a different story, they know that youkais are a thing, and if they are reminded that a certain type of youkai exists then those youkais get the faith they need to live.
Since Yamabikos don't seem to make their presence too much noticed then moving a small group into the village would help.
>"vampires exists, one tried to blot out the sun with a red mist"
>"onis exists, one threw a gensokyo-wide party"
>"yamabikos exists, one live just next my door"
/jp/ get everything backwards, they idol youkais like Rumia and Flandre, and considering that humans that are not citizens of Gensokyo are not covered by the spellcard rules, encountering them equal to "Death" of you are lucky and "Very slow and very painful" death if you are not.
Since Yamabikos are not dangerous (in the sense they won't kill you on the spot to get your blood / flesh / ass-soul / brain / whatever) /jp/ hate them.
In other words, a good rule of thumb is "If /jp/ love this type of youkai then is better to avoid them"