Upsides of disallowing author trading include

The pros and cons can vary greatly depending on the type of market. For personal markets, depending on the goal of the market it may make sense for the author to trade or not, and it's usually a good idea for the author to state their trading policy up-front. But this question is more about non-personal markets.

What I'm thinking of here would be something like if markets default to not allowing author trading but it can be optionally turned on. But the specifics could be anything that seems like a good idea - suggestions welcome.

https://manifold.markets/1/repost-under-what-conditions-is-it

https://manifold.markets/Yev/what-of-manifold-users-think-its-so

https://manifold.markets/LarsDoucet/is-it-acceptable-for-a-market-maker

Note: I would rather move away from the model of author having full control over resolutions, towards one where authors resolve most questions but in cases of dispute the final authority rests with a resolution council of some sort. 

 . But if we're still stuck with authors deciding all resolutions, it is possible it may be overall good to not allow authors to trade.

This question resolves to my subjective belief (credence) that if most markets disallowed author trading, that would be a net benefit for Manifold.

I'll form my belief based on the discussion in the comments, so please let me know why you think it would be good or bad. If you have an opinion you'd like to register, note that I take persuasive comments as much stronger evidence than just betting up/down. Betting up/down is essentially a bet about what you think I'll be convinced by and will only minimally influence my resolution.