It's well settled, but not very useful. We still teach Newton's laws of motion, even though we know they're wrong, because it's a lot easier to work with than Lorentz transformations, and most of the time, the result is just as useful (eg, the Apollo missions used Newton's equations). When introducing chemistry, it's much easier to understand a water molecule as a combination of two hydrogen atoms and one oxygen atom than it is to understand it as fields representing the two elements interacting with fields representing fundamental forces. Heck, in order to even explain the forces, you would probably need to introduce particles.

Because it is way more intuitive to think about particles, at least at first. For example, particles have mass and momentum. Fields do not.