There are lots of ingredients out there that you'd never want to eat on their own, or with them simply perched on top of your food. These things get mixed in--ingredients like baking soda, raw eggs (usually), dried chili peppers and worchestershire sauce.
You wouldn't eat beef or chicken bouillon cubes on their own (unless you're a freak!). So why would anyone set a whole anchovy on top of a pizza and eat it just like that? It needs to be chopped finely and mixed into the sauce or distributed judiciously, with other ingredients layered to accompany it. I've met few people who like anchovies, but I think it's because they don't know to do with them. Anchovies are ingredients and thus to be used, not foods to be consumed whole, unless you're one of those rare people with a sodium deficiency.
I made pissaladière for dinner last night, the primary ingredients being caramelized onions, anchovies and kalamata olives on a flaky pastry, sort of a southern French version of pizza. (As you can see, I cheated and grated a bit of a basque cheese over it.) But the anchovies are minced and dotted throughout--they're an ingredient, not a topping. So rather than getting a mouth full of fishy saltiness (or salty fishiness), the anchovies become a subtle part of the flavor profile, one that helps make the whole greater than the sum of its parts. It's all about balance.
The same goes for adding salt to something sweet. Ever wonder why recipes for cakes, pies and cookies call for a touch of salt? It helps balance flavors. Try baking two batches of cookies, one with amount of salt called for in the recipe and one omitting it. Do a taste test. You'll notice the difference, and the more well-rounded flavor will be in the batch containing a smidge of salt. You won't actually taste the salt. You'll just be aware that the flavor is better.
So if you come to my house and I feed you the best spaghetti sauce of your life, it will be because there are ingredients in it that you never thought to put in there yourself. They're probably ingredients you don't even think you like. You'll be surprised by how much you do like them--when they're used properly.