Operating a crane and positioning a truck to a crane unload or load is two entirely different things.
Flatbed is a rewarding but challenging career. Yes there is quite a bit of backing, but it depends on where you load and unload. If you do a lot of job sites like I do, then there is quite a bit of backing, sometimes even blind backing. Also because of the nature of the flatbed, you cannot maneuver like you would in a reefer or dry van. Loading and unloading, tarping and untarping can sometimes be time consuming, but if you are the kind that doesn't mind getting dirty, loves a challenge, likes the physical exercise, and appreciates a job well done, then flatbed is most definitely the way to go.
That's great, being able to run a 70 ton crane is a great skill to have. But we shouldn't let our preferences on where we operate heavy equipment influence the responses we give the op on the topic of driving a van or flat. He isn't getting stuck in the link belt when he shows up to load.
I have done both. I currently am doing van. I back more often as a van driver, but the backing on spread axle flat was much more complex at times. Don't ever listen to a van driver who says flatbedders can't back, they are just jealous of the flatbedder.