Sure, but the Speed Graphic had the advantage of being available before and during WWII. And when it came out, there were a LOT of lenses around in barrels, even though the lens sold on the camera was almost always in shutter. The other reason for the focal plane shutter, of course, was higher shutter speed. When shooting in full sun with the faster films of the day (equivalent modern ISO 250-400), it was completely practical to run the shutter to maximum tension and smallest slit for 1/1000 -- which nothing else could do before about 1950.