Dropshippers add range and access to market segments the manufacturer, or wholesellers, cannot ofer. These dropshippers are able to go after small customers with low order volumes. So they indirectly add value by increasing revenue.

they also cut out other middlemen like wholesellers and brick-and-mortar retailers. Done well, and at scale, this could be one of the more serious thrats for Amazon in the future.

> These days, don't Chinese companies mostly list the products on Ebay and Amazon themselves?

Yes, it's pretty standard to find the same company with store-fronts on AliExpress, Ebay and Amazon. It's sometimes worth checking for differences in prices though due to lag in updating each catalogue.

Faster shipping, added support, ease of returns. I am sure there are many other ways those "useless middlemen" could also add value.