In the film camera world, anybody that was any kind of pro used a medium format camera for weddings. If you showed up with a 35mm SLR camera, you would be considered a rank amateur.
The reason being is that roll film such as 120 vastly outperformed 35mm film.
I used to shoot weddings with a 120 Twin Lens Reflex camera, and it was much higher quality than any 35mm SLR camera at the time (which I also owned, but did not use for weddings). And the Twin Lens Reflex only cost as much as a moderately priced SLR.
But due to their nature, a roll film camera, and Twin Lens Reflex in particular was not any good for action or general photography. They were more adept for studio work and weddings.
The medium format advantage is a bit less absolute these days. You can buy a medium format digital camera, but prices rivaling the cost of a new Corvette, only the most accomplished professionals can afford them.
Bottom line - larger format produces higher resolution photographs.