It's not stupid at all. There are countless articles on it, including from fangraphs. It doesn't need to be reduced to zero, but the 4SM clearly should dominate unless the 2SM has the type of vertical movement to make a real difference. If it's predominantly horizontal (like Stroman's) then it's a bad pitch. It's only compounded if the grip and spin is unusual (like Stroman's) and can cause muscle confusion which can impact other pitches.