Is it really impossible to print several items in a folder at one time?
Not entirely impossible. It depends on the file type. This tip works best with things like rtf or txt files. If you have a printer queue open (System Preferences > Print & Fax > Select a Printer > Open Print Queue) then you can drag a group of files from DT to the queue, and they will be dispatched to the printer one by one.
You won’t get any of the benefits of the print dialog (page settings, paper, etc.), but you’ll get quick output.
On the other hand, for other file types the print queue will invoke the external editor for that file type, and not print it. Just experiment to see what works for you.
A variant of korm’s tip is to use printer queue apps (in ~/Library/Printers) as drag/drop targets, e.g. by leaving them in Dock.
I do wish the developers would make this a lot easier, but thanks very much for the tips. Appreciated.