I don't think it is just lack of critical thinking on the part of general public. I think that there are also some cultural contributors - it is often deemed uncivil or rude to call lie a lie. And if you want to appear impartial, you will need to make things sound middle - softening some stances and making others stronger.

You cant actually distinguish fact from fiction by logic alone. You need specialized knowledge for that, the rest of us you need to decide who to trust.

People who gravitate toward conspiracy theories tend to be intelligent and tend to question things they read. They then proceed to build wild theories, beyond possibilities of dumb people.