There is nothing saying they can't. You might be confusing it with something else. Oni's are just very honest/don't lie(with Suika kinda skirting that rule), so whatever a Satori youkai would read would pretty much be whatever they want to say anyway.
The main OS should be in here some place, but there nothing but all this beer.
But I'll just scare 'em if I go see how they're doin'...Starting day two of celebrating a year since Yuugi-sama left!What colour is your blood!!?When the Party's OverParental AffectionWonder if the folks on the mountain are gonna catch cold or somethin'...Gotta bear with it here for their happiness…Uwah! A youkai from the Underground is attacking us!!We'll drink today as well!