> create a neutral evaluation of the goods these rivaling organisations produce
Well... They mostly facilitate the evaluation of the goods. The evaluation itself is still done by scientists and scholars that are not employed by the publishers.
If those would routinely abuse the power bestowed upon them, they would threaten the magazines. Its in there own best interest to not abuse there review-powers, or there reputation could be ruined by the very same marketplace.
You cant just open another marketplace at the same location, because that has you at a automatic disadvantage. You could however ruin the marketplaces reputation, trying to shift customers to yours. You can also, wrap the market-place as in- provide a vital layer they need to function, and thus turn them into a organella of a bigger market-place.
Well... They mostly facilitate the evaluation of the goods. The evaluation itself is still done by scientists and scholars that are not employed by the publishers.