That's your definition. Under that definition, MOST of the men, and some women who build Tactical Rifles, or even Custom rifles, aren't gunsmiths, sir. They use the Remington 700 action, suitably modified, a custom barrel, modified to fit, and various parts and pieces, either Remington, or from other small manufacturers, to "assemble" the rifle. Very few gunsmiths make their own actions today, or their own barrels, bolts, or even stocks. You'll be hard pressed to find a pistolsmith making their own pistols from the frame up, as well.
Yet, at the end of your statement you say that "if you can't manufacture or repair a firearm, you are not a gunsmith." There's quite a difference between those two levels.
While most gunsmith's of any note are also FFL holders, they are 01s, not 02s, manufacturers. The price of admission to that level is steep, and the various licenses for business, and record keeping, prevent all but the most successful from ever taking that step.
Not every gunsmith is a Yost, or a Clark. Most are small-town businessmen, with limited exposure to all that many guns. Their living is mostly from mounting scopes, cleaning guns, and the occasional part replacement. Many have no interest in enlarging that particular spot, as they are comfortable there.
Deciding that not wanting to work on your particular problem gun is a reflection on their abilities, is just as wrong as what you accuse them of being. It's more a reflection of their attitude. Of which, it appears, there's plenty to go around.
Pick up your bag of parts, and head out the door, remembering this for the future. They didn't get your business, or your money. At least they were honest enough to tell you up front that they wouldn't work on the gun. Too many people would have gouged you for sub-optimal work.