The problem that I imagine you see with this, is that it doesn't conform to a particular, special, notion of fairness that you think the market should have.

Informed parties have an edge over uninformed parties. This edge is "unfair" if you believe the market should be a lottery. The market is designed to pay people with accurate beliefs, by taking from people with inaccurate beliefs. Everyone's belief is valued based on its accuracy, and the market is fair in that sense. Fairness is actually irrelevant to the societal good the market provides, which is to produce accurate prices. A third party, who doesn't participate, shouldn't care about the market being "fair", they should care about it giving good information.

> A similar issue is that of market manipulation, since many markets in these platforms can be directly manipulated by participants in manners as easily as spamming some words on an earnings call.

If you are betting on what a person will say, and the person knows about the market, that is a chaotic system. If you bid the price away from max entropy then you deserve the outcome.