I haven't heard of the Loader model, but as an (ex-) Particle Physicist, I should point out that photons are just one example of the more general phenomenon of gauge bosons. In terms of the particle content associated with nature (and the predictions the _existence_ of those particles imply as emergent phenomena from "gauge theories" in quantum field theory), the photons of electrodynamics as well as their counterparts, the weak bosons of the weak force and the gluons of quantum chromodynamics, all make very specific predictions about how certain particles ought to behave and the strength with which they should do so.

In that light, photons (and to a lesser extent, the other gauge bosons) play a significant role in theoretically calculating the dipole moment of the electron (how strong the electron interacts electromagnetically) which has been calculated to about 12 decimal places theoretically and experimentally measured to roughly the same precision. And the prediction fits _beautifully_, I believe it is the most (numerically) accurate prediction in all of science. So at the very least, photons are meaningful descriptions of some kind of quantum field oscillation whose existence is, implicitly, extraordinarily well determined.

Typing this in a rush, but just to say, photons are a very specific kind of energy quanta, and I don't think the loader model really replaces them in that sense.