In the past, it was "obvious" to most people that the Earth was flat.
They could see and check by their own experience: the Earth was obviously flat, just look at the horizon and see the flatness for yourself.

There were a few nutcases out there saying otherwise, but who would believe them, if every major institution and almost all people already knew that the Earth was flat?

The ones that contradict authorities must be silenced because they are a threat.

We are in the middle age of information, and everybody knows (OK, most do) that the Erath is flat.

You can see that on TV, and every authority say that: the WHO, FDA, CDC, and publications like The Lancet, etc.
Then, of course the Earth is flat. Who say otherwise is a nutcase. But a dangerous one...
They must be all silenced because they are a threat.

Yeah, the flat-earth believers are a good example of what is happening (of course I mean the flat-earth believers of the past).