Such a normal mixing techniques today, is the ability to use the original source as a sidechain to itself. Mostly used with wet effects, where you for instance duck/sidechain reverb or delay when the original source is playing. The splitter would be amazing for exactly this, but it is not possible because of the routing system (maybe because sending the signal to itself could end up as a feedbackloop). Now maybe there was a simple solution to this, in how you could select the sidechain source.
This is really keeping me away from the splitter for instance. This is also a normal feature in some of the other DAWs that have rack/chains like this.