It's certainly not the only way
I hunt massive tracts of land. All public. Heck I think one of my places is over 60,000 acres. This is active coal/timber land, and killing birds over decoys would be laughably easy. Our birds routinely congregate in log landings or reclaimed strip mines. It would cheapen what makes our mountain hunting so special and difficult by riding a 4 wheeler to one of these places and staking out a decoy.
I cut my teeth hunting huge ag fields in Alabama. Some as big as 500 acres. Decoys were illegal then, and we learned to hunt field turkeys. Sure we got our asses beat most days, but we also got decent at killing those field birds with just a call.
When I moved back home after college, all I had to hunt was small farms and never messed with decoys because they were taboo to the turkey hunters I crossed paths with in Alabama.
I firmly believe that's the difference, people who have hunted turkeys for a long time are far less likely to use decoys than the new hunters. Old school versus new school. Traditionalists versus Kill at all costs no matter the tactic.
I also as stated earlier. Firmly believe decoys are one of the main reasons for our dwindling populations. It makes it too easy, too many dominant birds are killed, and it is effecting nest initiation