I can. R0~5.7 has dropped below 1.0 in many mask-averse stay-at-home regions, which I consider compelling evidence of efficacy in an adverse environment, under common-sense priors informed by the medical literature.
"This number is below 1.0" is not, by itself, an argument that some particular social policy was necessary or effective. An argument that lockdowns were necessary would at a minimum need to address the questions of "would a less strict policy have sufficed" and "will the long-term outcome after lockdowns end be different".