Are you aware of any meaningful contributions they have made to overall “progress”, aka advancing the general capabilities of humanity?
Not sure if this meets the bill, but off the top of my head I thought of the HIV sequence database which has been around since 1988.
I think you grossly underestimate how hungry scientists are to prove each other wrong. This is part of how you build status to begin with. Yes, there are collaborative relationships, but there are also a great many adversarial relationships. There is no top-down hierarchy, so silencing dissent in this manner is unavailable.
I do think some degree of self-censorship occurs, absolutely. Are there biases, sure. But I find the claim that any given person is so influential in epidemiology that there is a conspiracy of silence lasting quite this long rather absurd.