If you're referring to Feynman diagrams, sure in the modern treatment they don't mean what people usually think they mean, but it's also not accurate to state t

If you're referring to Feynman diagrams, sure in the modern treatment they don't mean what people usually think they mean, but it's also not accurate to state that particles don't pop in/out. It's a simplification for sure, but you really do need to enumerate all the field configurations and there is really no difference from a first principles point of view between your "physical" particles and the "off-shell" excitations. You can argue about the reality of the contributing terms but it sure looks like they're needed or you won't get the right results.