FYI that's the article, in particular "der/die/das" are the definite articles.
"Incredibly stupid" sounds a little derogatory. They are not particularly necessary for understanding the language, the correct gender/article for certain nouns are even subject to heated debate between regional dialects, and I agree, if you are coming from a language without these rules it might be hard to grasp/integrate. Nevertheless, I would not go as far as to say they are incredibly stupid.
Consider, English also has he/she, him/her, his/hers. You just got rid off the "the"s, AFAIK (or German is the only Germanic language that adopted it from Latin, but I am no linguist).
But gender is the easier part, the cases make it difficult: Similar to the English "he/him", we have declination of articles: "einen/einem/eines". This seems terrible for English natives. Together with constructs of "den einen/dem einen/von einem/vom einen/zu einem/auf einen/auf einem", so you need to memorize ways of saying things and at the same time apply the case accordingly. It can make a huge difference in what you are trying to convey.
"Von einem ..." is "... of one" (indefinite article), where
"Vom einen ..." (Von dem einen) is "... of the one" (dem is the article, einen is actually a counting pronoun, not sure this is the right name).