Useless ? Massive exaggeration there I assure you. Not optimal for Turkey, but neither is an 18” gun with a 3” chamber.
Never say Never, a hunter and a turkey could accidently stumble into each other.
But typically, you're using great stealth and camouflage, and careful calling, trying to get a turkey to come within 40 - 50 yards , and turkey specific guns have very tight , very center dense patterns , to put multiple smallish pellets ( 4 , 5 , or 6 , or duplex loads combining two of those ) .
A cylinder bore would have patterns of similar density at 15 - 20 yards . Never say Never , but it is very atypical to call in a turkey that close .
Purpose built Turkey Guns frequently have short Bbls of 20 to 24 inch , and the difference between 18.5 and 20 inch is negligible . 3 inch chamber , shooting 1.75 to 2oz of shot . Short Bbl is no hindrance, balance for swing is moot . A turkey gun will be aimmed much like a rifle .
Patterns on target are what matters.
I'm not hating on shorty shotguns . ( But I do prefer my shorties with a little Choke, and once bought one primarily because it had threaded 20 inch bbl .)
If the question was more generally " can I hunt with this gun " , my response is Sure !
Be cognizant of distance , and select Shot Size on the smaller end of the gennerally accepted sizes to keep up Patten / Hit density . ( i.e. my #2 shooting & hunting partner swears by #4 for squirrel. Particularly with the open ( no ) choke , I'd be using #6 . )
Rabbit , Squirrel, Quail , Grouse , Dove , etc, you're ok. You will have to be selective about the distances, and pass up shots that could be taken with a Modified Choke . ( Context of the intermediate constriction between Full and Improved Cylinder .)
Deer , Boar , Bear with Slugs , no issues , and probably preferred for handier for heavy brush . ( Before Fully Rifled Shotguns were common , we hunted with smoothbores , and it seemed normal to us . Random brand of slug * probably * within Minute of Whitetail * to 50 yds . Might take trial & error testing to be confident at 75 yds . )