I'm not an epidemiologist, but I've written code for people in various fields. I knew code, they knew the domain. All of them knew things that I would have fucked up, if I had tried to write the code with just my programming knowledge and my big brain, without their domain knowledge and experience.
A university education teaches you something.
I assume that epidemiology is like the other university fields — when lay people come and show that the epidemiologists are wrong about epidemiology, they're about as likely to be right as the people who write to maths professors claiming to have found a method of trisecting an angle. And the people with the novel claim and the missing education bear the burden of proof.
I dont think that comparison is universally applicable. I wouldnt rule out that this is a lot more similar to a Math Prof telling you that the p-values in for example your psychology paper are nonsense and correcting you.
edit: Not saying studying Math qualifies you to design and run studies in Psychology. But once you break down tasks enough you will often find them to be the area of expertise of another discipline. Often its very easy to tell when the Professor that taught you something in university is from another department.
A university education teaches you something.
I assume that epidemiology is like the other university fields — when lay people come and show that the epidemiologists are wrong about epidemiology, they're about as likely to be right as the people who write to maths professors claiming to have found a method of trisecting an angle. And the people with the novel claim and the missing education bear the burden of proof.