The complete kitchen knife set must be able to handle the following functions:
In most home kitchens, many of these things don’t come up often. The problem is that there is a lot of variability. I know lots of people who have never taken a whole fish and broken it down into steaks or fillets. Vegetarians obviously don’t need meat knives. Getting whole bone-in meat cuts is often very expensive because you end up paying as much for the bones as for the meat itself, so lots of meat-eaters never need meat butchering knives.
On the other hand, not every function needs its own knife. For instance, a Chinese cleaver or a chef’s knife is fine for vegetable cutting and mincing, and a chef’s knife will do meat slicing too. A deba-hocho, the Japanese fish-butchering knife, does well for not only that task but also dicing and mincing, which an usuba does not do. So it all depends how the bits and pieces come together.
What everyone needs is vegetable cutting, chopping, and mincing. At some point, everyone is going to need a detail knife. Beyond that, it depends what and how you eat.