Even more than that, just proving Maxwell was right was a key stepping stone to all of modern physics. Maxwell, not Einstein, was the first to show that the speed of light is invariant, and Einstein's Relativity was a framework for explaining how tf physics works if that's actually true. Prior to Einstein, physists all just kind of assumed there was some flaw in Maxwell's theorems to lead to this crazy speed invariance, but as the evidence just kept piling up in favor of Maxwell, they started having to wrestle with the uncomfortable thought that this could actually be true. In this sense, Hertz can also be thought of as an important step to Einstein and beyond, and almost all of our modern technology.