I think the default that electron is a wave is taught us first because of historical reason. You have to understand the newtonian universe before the quantum else it would be to complicated.
The atomic model was first made with electron on discrete observable routes. The next step was the thinking that they have to be kinda stable and quantized so that they are not emitting photons as default. So the orbital modell follows.
So after this with quantum mechanics it turned out to be, that everything has the wave particle duality and these behave all also like waves, but the de broglie wave length is mostly so small that it isn't measurable. But scientists proofed that the double slit experiments also works with carbon molecules.
It would be nice if the kids are learning all this, but also in Math you don't start with unknown variables you make them first understand actions like addition multilication etc. Afterwards you can build up your system step by step. But our brain just needs first a simple modell before it can imagine more complicated things.
Also the quantum mechanics is not the least and best theory I think the quantum field theory adds a bit more to the states of the quantum mechanics since there are fundamental problem when combining it with relativity.
But, you don't can add up just the theory you have to find new ones and an interesting question is, if we find them be seeking valid equation and put them together. In "Emperor's Mind" Roger Penrose makes a good approximation with Goedel theory. Goedel actually proved that not everything which is valid is proofable so you have to assume that some of your things are true and build your univers upon it. But at the end every theory is either disproved or not already disproved.
Hopes this helps Greetings