Mark,
I'm sure you know you were fishing the Bull Shoals tailwaters at Calico which is somewhat dependable fishing. At the confluence, it depends on where you are fishing, but not far upstream from the confluence, the fishing in the Norfork tailwaters is not that easy all the time. It is often challenging and downright frustrating at times. Unless, of course, you're casting corn and powerbait. Even then there are no guarantees.
Yes, anyone can go to any river, lake, pond, or stream and fish without a guide and catch fish. (Even THIS "blind squirrel" stumbles onto an acorn at times... ) But, hiring a guide can make for a more productive and rewarding trip if you do not know the river. ESPECIALLY if you are not familiar with fishing tailwaters and ESPECIALLY the safety factors thereof.
You might go to the Norfork tailwaters and land a 25 inch Brown. But, I'm willing to bet the farm that if John Berry is standing beside you, your chances of that are much, much higher.
And I'm not a pro guide (or even an amateur one) and John doesn't even pay me to say this... (Unless you just WANT to slip me a twenty at Sowbug, JB... )