So by that interpretation...anyone that builds a model is a professional?

We all have the required skill to build a kit, and can do research to "reproduce a believable replica" (whether we do or not), I fail to see how one could be called a professional just because you have the skill to build it and do the research to make it as "believable" as possible.

Someone that searches out blueprints of the real thing, and reproduces the item in said blueprints, in scale from scratch, as done the research and obviously has the skills to do it as they scratchbuilt it....doesn't mean (to me) that they are a professional modeler.

If they are being commissioned to build it, or build it with the intent to sell it to someone, then yeah...but just the act of researching and building it? No.

I can look up a recipe on line (research) gather all of the ingredients and cook it (building it), doesn't mean I am a professional chef.