The medical field, or at least its public-facing portion, seems to be full of people who are reluctant to propose anything novel if there aren't rock-solid studies justifying it, even when it's clear (even to laypeople) that an analysis of the expected costs and benefits does confidently justify it.[1][2] It's a similar kind of thing to "no one ever got fired for buying IBM". And if you look at the incentives of medical spokespeople, do they actually suffer if they give bad advice? Is Dr. Mike Ryan still executive director of the WHO health emergencies program? His Wikipedia page still says so; its link to the WHO website has rotted.

Given that, it's precisely these guys, outsiders who think they're smarter (or less bound by rules or whatever) than those spokespeople, who are in a position to give us some of these important pieces of advice. Of course, that means you have to take them on evidence/argument rather than on authority. But it seems like the evidence/argument here obviously stands up.

[1] https://www.cnn.com/2020/03/30/world/coronavirus-who-masks-r...

[2] https://slatestarcodex.com/2020/03/02/coronavirus-links-spec... , search for "bungled its coronavirus response pretty egregiously"