Wikipedia is the most accurate encyclopedia to date
How did you determine that?
Wikipedia is built near-purely on second hand sources, which is how all encyclopedias are intended to be constructed. As long as one ensures the validity of the second hand source used, encyclopedias are great resources.
True, but basically nobody does check that the sources are valid, and they often aren't.
Because I see the things they're getting from Wikipedia and I am them, and they admit they didn't actually check the sources.
How would you determine that a cited source was wrong?