No it actually does not, it increases the spread and creates a pressure build up compared to being open, you are initially adding volume into the toilet when you flush with the lid closed this pressure build up is greater and spreada the particles further. You are essentially creating a shit nozzle on the sides of your toilet. All the lid does is help the particles become bigger so there are fewer visible particles but they are bigger and travel further, while remaining airborne longer due to their velocity.