Two main arguments, why to fear crowd jury:
- In ancient Athen people might have been able to obtain third, second or even first hand knowledge, in modern times the informations will likely be received by a (very) unreliable mass media.
- Digital informations can be faked, some forgeries might be found out with crowd intelligence, but there is no guarantee.
In cases of big interests the danger of fraudulent manipulations is high, in cases of small interest, a minor misinformation of some crowdmember might not be detected.
Of course the same can apply to traditional court rulings, but the proceeding is easier to oversee.