פירוש על סוטה 43:7

They issue halachic rulings from their mishnayot -- it says "they erode the world" with mistaken teaching, since they do not know the reasons of the mishna, which leads them to compare it to a thing to which it is not similar. And further, there are many mishnayot which are said like Ploni, and Ploni is an individual voice and the halacha is not established from such. And further, they do not know about the disagreements (machlokot) of the first/former tannaim, who the halacha is like -- and therefore they teach mistakenly.