Because the aggregated weighted result ranking provides a more useful page rank than any individual search engine, and if any search engine tries to (accidentally or otherwise) stuff specific results into the top ranks, it doesn’t matter. It’ll be deranked because no other engine displays those results highly. In a similar manner, it deranks targeted SEO attempts unless multiple platforms are targeted.
Don’t get me wrong, it still has its problems. For example, if the individual search engines all get a bit too samey, then it will as well.
It’s interesting that the effect magnitude and significance are both higher for negative emotions than positive ones.
I mean, it’s fairly common knowledge that we remember negative emotional experiences more strongly than positive ones, but it’s interesting to see that supported here.