Splitter belt dragging upgrade

[JamesFire]

Dragging higher-level belts over a belt line auto-replaces any belts and underground belts you drag it over, but not splitters. It feels weird that splitters are excluded from this.

[Illiander42]

Did they say why they did it this way in the FFF that showcased this?

There's got to be a reason, I just can't remember what it was.