Why are atoms particles?
According to wikipedia an elementary particle or fundamental particle is a particle not known to have substructure.
Moreover, I've learned that such a particle satisfies the Dirac Equation, and this is a mathematical condition to be respected to deserve the appelative "elementary", because among the hypothesis Dirac used there is a limitation in the degrees of freedom.
One of the proofs of the non-rotation of the electron, is the negative argument which negates that the spin represents a real-space rotation of a sphere (the electron), using its gyromagnetic factor and the limit velocity $c$. In this sense, the electron doesn't have any additional spatial degrees of freedom.
At last, in QFT, elementary particles are assumed to interact in point-like collisions.
Therefore, I'm wondering about the deepness of the concept of point-like particle. Is this just a model, an approximation, or when we deal with QFT and similaria we relate to this concept the real existence of point-like particles?