That is true, although if you want to take a lot of shots, most 120 cameras don't get a lot of images per roll, so you would need a lot of backs, and even 30 years ago, the backs cost more then many 35mm camera bodies. I would hate to see a guy try to do a wedding today with a Speed Graphic when most people expect to have a couple of million frames to look through on your iPad after the reception.... Doesn't mean you can't use an SG for some shots, there is no better tool for that poster sized print of the bride and groom to go in their new home.... Like I said though, a good photographer has more then one tool (camera), and knows how to use all of them. The key isn't the tool, it's using the tools to get what you want. With the minimum of time taken. Say you get $500 to do a wedding, you spend 40 hours on the computer to get a bunch of digital images to look like they were shot on film, your materials cost is $75, your depreciation on your camera is $10, you spent 5 hours on a Saturday doing the shoot. Congratulations you made $9.22/hr....
Shoot the same thing on film, you spent $150 on film and processing, your time is 5 hours plus the hour to the lab and back, you made $58.33 an hour, this is why some wedding photographers are going back to film, plain and simple.
I do not need to take thousands of photographs to capture a wedding. I make each photograph count. Hasselblad back are much cheaper now, I generally pay about $100US per back, and I discovered that they are even reusable!
Warning!! Handling a Hasselblad can be harmful to your financial well being!
Nothing beats a great piece of glass!
I leave the digital work for the urologists and proctologists.