Subcategories or subchannels

i'm creating a study/educational discord server, and i feel as though it's super restricting not being able to put categories within another categories to link a subcategory to a main category. for example, in math you would want trigonometry or calculus, but instead of that being within a set "math" category, it needs to be a different category all together. i don't think i'm the only one with this idea, so i'm not sure why you don't implement it into discord, it could definitely clean up servers and make it extremely organized. for now i'm using a category as a indicator and another one as a breaker to split different categories, and honestly speaking, it's a pain, and having a feature for subcategories would solve all of that.