Even for the flat Earth theory it's hard to dismiss it offhand. I mean sure there are plenty of experiments you can do to show that it is pretty close to a sphere. But who do you trust to do those experiments?

Either the person fact-checking needs to do the experiments/research themselves (which doesn't scale well) or they need to trust other people to have done the experiments. However at that point you're simply placing the word of some people above the word of others, which is not objective at all.

And even assuming you've actually picked honest people acting in good faith you're still relying on people to not be confidently incorrect, which I can fairly confidently say is always going to go wrong at some point.

All the various people who have done them, some of which can be repeated by anyone motivated enough, and all the technology that relies on it being the case. This was known to the ancient Greeks. One even calculated the circumference within a reasonable accuracy.

Certainly the architectural drawings of my house do not include a "bulge" in the basement due to heretical sphericalness.

All discussion of my basement floor being flat within about 1/2 inch need to be censored by big brother to save us all from free and independent thought.

The purpose of arguing about what should be censored is to distract from the argument of should there be censorship at all. Classic divide and conqueror strategy. Nobody ever gets asked if they should have concentration camps or not, they only argue about competing paint schemes and honorary mottos.

And when they argue that the earth is flat, they aren't arguing about whether it's flat on the scale of my basement.

Spelling out those applicability conditions explicitly is critical in research publications (but even then, only used for the topic under investigation). In all other contexts such pedantry is impossible. My 2c.