Aside note, but: "Hear, hear!". Until years ago, I would normally use that kind of mockery of absurd ideas by reciting adherence to impossible beliefs and opinions, with the implicit that nobody would hold them unless insane, so of course I was being purely ironic.

I do not do that anymore. The world is clearly full of cases for which absurdities are tenable - not by an odd minority, but by "(pseudo)random people". If you declare them, the presumption of irony is gone.

I'm not sure what dead serious means, but the comment was quite literal and simple.

Which is not to say that I approve, merely to state the root explaination for the insane state of affairs. You could say dead serious in the sense that I wasn't joking, that really is the explaination.