Physics Question

I've come to the realization that a particle which has no mass is not necessarily without extent [or dimensions], though most physics books/professors will lead you to assume that they're some kind of material-less non-entity. While I still have yet to see any evidence [let alone proof] that either photon or a graviton actually exist, I think that a particle with no mass makes sense and violates no philosophic law.

First it's important to note that mass in the scientific sense is not a thing in itself, it is a fundamental attribute of matter, which causes the matter to interact gravitationally with other matter. It's the common, imprecise, usage of the word that refers to some amount of material. So, a particle without mass is merely a particle which because of its nature lacks the fundamental ability to interact gravitationally with other matter.

This realization still doesn't answer my questions of how a photon or graviton, which has no evidence for its existence is philosophically different, or less of a problem, then action at a distance?