I think there has long been a debate between what should fall under Tiny and what should fall under 1/6 scale. I, personally, think that the BBB dolls like Bei and Bao and Isabella should fall under 1/6 scale because they are 26cm tall and, while not adult proportioned, are more slender build and less child-like than other resin 1/6 dolls - but I've been in the minority on that.
Again, personally, I consider it "tiny" if it's in the Pipos animal doll (about 5 inches tall) on down - which would leave all those Yo-sd type dolls in a sort of limbo I suppose.
Since I've never seen one of the SOOM small size in person I really can't speak as to their tininess - but if they are anything around the size of my CH Ange Ai, then honestly, I just can't call them tiny to myself