Indeed, Rabbeinu Manoach (Sefer HaMenuchah, Laws of Chametz and Matzah, Chapter 8, Halacha 2) provided a different reason: "And we practice with karpas as a remembrance of the coat of many colors that Jacob our father made for Joseph, which led to the events that caused our forefathers to descend to Egypt." This is based on the Talmud (Megillah 16b): "Rava bar Machasya said in the name of Rav Chama bar Guria in the name of Rav, because of the weight of two sela'im of fine wool that Jacob gave to Joseph more than to his other brothers, the matter was set in motion and our forefathers descended to Egypt." Similarly, this is explained in Rashi's commentary (Genesis 37:3): "Pasim – a term for a fine woolen garment, like 'karpas and blue' (Esther 1:6), and like the coat of many colors of Tamar and Amnon (2 Samuel 13:18). And a Midrashic interpretation, referring to his troubles, as he was sold to Potiphar, to the merchants, to the Ishmaelites, and to the Midianites."