It's annoying to have to remove a splitter because you need to place a belt one "stackable conveyor" higher.
Example, have a belt go between two stackable conveyors at the same height. Add a splitter in the middle of this belt. Then, add a stackable conveyor on top of the previously placed stacks and try to run a belt to them. The splitter will block you from placing it. However, if you remove the splitter, place the belt, then put the splitter back it works.
The height of the splitters and mergers shouldnt interfere with the belt above, if its one conveyor stack above.