Unfortunately, I cannot recall a single discovery in physics in the last half a century that was not made by someone who jumped through the usual hoops. I have met, however, an occasional person who learned grad school-level stuff on their own, but they did not manage to go any farther. My suspicion is therefore that all that negative selection in science, while annoying, does not do a lot of harm compared to potential alternatives.

But you don't get to observe any of the discoveries in physics that haven't been made. If a good university education is markedly better for learning physics than autodidactism, then the people who don't jump through the usual hoops will be inhibited by an inferior education and won't be in the position to make discoveries that a person who did jump through those hoops is.

If receiving a high level education and having access to university resources is effectively a precondition for making significant new discoveries in physics today, you would not expect to see people who did not go through the regular procedures making significant new discoveries in physics, even if the negative selection of academia filters out most of the best candidates.