So that when they squeak by it's less obvious, duh.
Just like it would be obvious if they won in a landslide.
Or if Republicans won, because Democrats didn't want to make it too obvious that they were rigging it.
Or if it was split, because Democrats would want to hedge their bets and get a small while while making sure it wasn't obvious it was rigged.
Basically...it's always rigged. Just ask Sidney Powell!