The main argument against light being "electron waves" is that there is not much matter out in space, so how could electron waves propagate? The reason is that light is a plane wave and the field does not drop off just from distance from the surface of the wave. So it can reach out as far as needed to propagate.
The field extends out till it moves enough electrons around to neutralize it. Normally this is a very tiny distance for visible light but in space it might be a few meters. Radio waves can be thousands of feet, so space density of electrons does not seem any trouble for them.
Imagine in deep space there is a place that light gets to but there was no matter after that for the light to propagate on. Then the matter at the edge would absorb the momentum of the light and be pushed on toward where there was not enough matter. So light from all the stars is working to keep a tidy medium for light in place.
I am told by people who seem expert in this that lasers entering a vacuum do not push electrons into the vacuum. Also, a vacuum tube with a positive plate absorbing electrons is still transparent. So there are troubles with this hypothesis.