Well I have no proof that it actually increases yield but I know it removes branches and leaves allowing more water to go to the remaining fruit. It also allows more sunlight to reach and penetrate the plant.
It has been my experience the fruit that I get are very nice sized. Maybe as it turns out pinching causes a lower yield but if they are bigger and sweeter due to better sunlight, I can live with that.
I mean piggy 🐷 meat, lettuce and a slice of beefsteak on toast, it doesn't get any better then that!!!
