There's nothing inherently more natural about cooking in the metric system, people just prefer base 10 these days. People balk at 4 quarts to an arbitrary gallon but love 1 liter being the arbitrary cubic volume of 10 ten-millionths of the distance from the Equator to the North Pole passing through Paris [but not quite].

Cooking by volume was natural before everyone had accurate kitchen scales. You didn't have a digital tare button in the 1800s but you did have a bunch of containers in common sizes.

what happen when you need 3/4 of a cup ? Or 1.5 cup ?

Generally you have 4 sizes: 1, 1/2, 1/3, 1/4. You just use a combination of 2 sizes (1+1/2) or multiples of your smallest size (3x1/4).

You usually don't need high precision for cooking, common ratios are good approximations (1:1, 1:2, 1:8, etc...). Baking is a different beast and I don't know how people did it before weight.

Also, fuck tablespoons and teaspoons. They should just be replaced with 1/16 cup and 1/32 cup.

We have the same measuring cups I'm sure you use for liquids. They have mL on one side, cups on the other and a scale for sub-sizes. We do have individually-sized scoops which are nice for over-scooping and just sliding your finger across the top to push off the excess and get the amount you need. It's not strictly necessary though. They come in a set where each smaller scoop fits inside the larger ones in a tight stack that can sit in a drawer.

The infinite granularity is ultimately unnecessary. Recipes don't call for 0.397 cups. I'm sure you don't see any that ask for 438 grams. If you do the math on a lot of recipes listed in both metric and imperial, you'll find that they're not even using the exact same amounts. The convenience of using standard measures tends to outweigh the flavor difference with plus or minus a percent of ingredient.