If we want local, small, or niche businesses to exist.
>do we need instant financial trades and people optimizing instant transactions?
If we want people to easily get a fair price when they want to buy or sell something.
the point again is that nobody says that certain mechanism of the market can have positive effects. the point is that way overestimated. we have extremely complex procedures that cost insanely amounts of money for stuff like ads. we could have a fraction of that power and people would still know about the products they need, etc.