because potions are spells. a potion is any liquid spell, like oils, lotions, baths, teas, brews and so on. while a tab would be nice, there should therefore be a tab for jar spells, candle spells, poppets, and any other type of spell, it would be a hassle. yes, having to sift through a bunch of non-potions to find one is annoying, but a separate section is probably not going to happen.
i understand why you're annoyed, i had to got through the same thing, but it's not that big of a deal. you're going to have to get use to searching for answers, you can't give up because you have to go through a lot of dead ends.