Saying “everyone knows this” does not itself turn a claim into a sound widely accepted premise. Claiming consensus and establishing actual acceptance are different; widespread acceptance is also not the same as demonstrative certainty.
For example, an advocate says, “All scholars agree with my view,” when there is no such agreement. The claim borrows the appearance of common opinion.
A careful reader checks the extent of acceptance, the relevant community and the connection to the conclusion. Being impressed by a claim is not evidence.