With konqueror for a very long time it was possible to split the tab vertical and horizontal multiple times, e.g. on large directory at the left and 3 smaller ones right. That is extremely helpful when copying data between many directories. As Dolphin aims to replace konqueror and konqueror is unusuable in newer releases please finally implement the feature to have more than two directories displayed and arrange them freely. Todays computers have extremely large screens. One or two directory listings is a waste. Using multiple instances is no adequate replacement.
As a regular Dolphin user (inside i3wm), I really wish this feature was implemented as well, even though I can easily rely on i3 to "split views" for me, aka by opening multiple Dolphin instances. BTW, the title should really be "multiple split views", rather than directories.
*** This bug has been marked as a duplicate of bug 168592 ***