Ok, I'm not touching the ECE thing; as noted, I'm not a theorist. I just measure stuff. I've taken classes in formal QFT, but I don't use it day-to-day, so it's a weak point for me. However, it seems a bit odd to describe things that can be produced in collisions and (at least in principle) fired at your enemies to kill them by radiation poisoning as 'illusory'. If you bang two electrons together, measuring the cross-section as a function of the center-of-mass energy, you will observe a classic 1/s decline interrupted by equally classic resonance bumps. That is, at certain energies the electrons are much more likely to interact with each other; that's because those are the energies that are just right for producing other particles. Increase the CM energy through 80 GeV or so, and you'll find a Breit-Wigner shape like any other particle; that's the W, and if it weren't so short-lived you could make a beam of them to kill your enemies. (With asymmetric electron energies you can produce a relativistic-speed W and get arbitrarily long lifetimes in the lab frame, but that gets on for being difficult engineering. In fact, just colliding two electrons at these energies is difficult, they're too light; that's why CERN used an electron and a proton in LEP.)

Now, returning to the math, my memory of this is that particles appear as creation and annihilation operators when field theories with particular gauge symmetries are quantized. If you want to call the virtual particles that appear in Feynmann diagrams illusory, I won't necessarily argue with you; they are just a convenient way of expressing a huge path integral. But the math doesn't spring fully-formed from Feynmann's brow; the particular gauge symmetry that is quantised is chosen such that it describes particles or forces already known to exist. (Historically, forces, since the theory ran ahead of the experiments in the sixties - we saw beta decay long before we saw actual W bosons.) If the forces were different, the theorists would have chosen a different gauge symmetry and got out a different set of particles.

I'm not sure if I'm answering your question, here? My basic approach to QFT has always been "shut up and calculate", not because of QM confusion but because I find it very confusing when someone says that a particular mathematical operation is "causing" something. I prefer to think of the causality as flowing from the observations, so that the sequence is thus:

• We observe these forces / cross-sections / particles.
• We know that by quantising field theories with gauge symmetries, we can get things that look very much like particles.
• Searching through gauge-symmetry space, we find that this one gives us the particles and forces we observe.