Should Definitions Be Democratic?

Collins, the dictionary publisher, is crowd-sourcing its next project. Jonathon Green is not pleased, since the dictionary "represents authority":

[T]he dictionary is not designed for second-guessing. If it is not intensively researched, edited, proofed and rendered as "true" as possible, why bother to consult it? Of course dictionaries are human inventions and subject to human failings. How not. Research continues and research means revision. All the better. But the days of Johnson's cracks about oats and Scotland are over and the aim is the disinterested assembly of material.

And if not? Then we have the Urban Dictionary. Every line a laff, but do we believe this farrago of misinformation, theorising, one-off terms and a level of "definition" based on a count of thumbs up and down?