Seems even having multiple selections we just can drag and drop items one by one, am I right? Basically having access to selected items & drop event I can code workaround & move them myself, but hope that we have it out of the box, do we?

Set TreeView selection type to multiple, select several items, try to drag, just one item will be dragged despite having several selected.

------------ADMIN EDIT--------------

A possible workaround can be implemented by using the OnDrop event when you have Multiple selected Items.