So, the left-side tine of the fork is usually a bit bulkier than the others—and that little notch acts as a pressure guide. The idea is you press the fork’s side into your slice of cake, and that notch gives you guidance for your cut as you press down. It’s not aggressive like a serrated knife or anything, but it will allow you to slice through soft layers—frosting, sponge, even that slightly-too-dense bottom of a store-bought sheet cake—without just mangling everything. In essence: cleaner cuts, fewer crumbs, less sad frosting smears.
Honestly, when you actually use it correctly—which, okay, no one tells you how to do—it sort of makes sense. You can elegantly cut into a wedge-sized piece with the slightest pressure; you never have to use a knife, and you can keep your plate relatively clean. It’s the sort of thing you wouldn’t think matters… until there are seven people watching you try to dissect a cheesecake with a salad fork.