In the Magic Kingdom, if one seeks the origin for most customs or etiquette, they would largely trace it back to the Royal Court, or even the Queen herself.
As the saying goes, "If the king likes slim waists, many starve in the palace." Although the Queen of Rose Palace doesn't impose her preferences on others, her fondness for sweets is indeed well-known. Naturally, many nobles of the Royal Court take the initiative to cater to her tastes, not only inventing various confectionary crafts but also standardizing a whole set of dining utensils designed solely for eating sweets.
Eventually, this dining etiquette was also conveyed to the people of the Kingdom. In the process of top-down emulation, not only did sweets themselves become the most popular and well-known category of meals in the Magic Kingdom, but "the ability to skillfully use dessert utensils" also became a mark of one's living standard.