No need to split the neutral. Say the switch controls a light. Where does the light get the neutral from?
Exactly. Since there is technically no need to split the neutral, in old wiring they didn't put the neutral in the box, they ran just the hot to the switch box and the neutral went direct to the light.
(IINM they had the wiring go directly to the fixture with another wire going to the light with a black and red wire for hot and a return)
Many of the modern switches just have a screw terminal. It is probably against code to put two wires on a screw terminal.
In switches with that flap the make it real easy to, don't know about code though.
click picture