When I started Traditional modeling had a clear meaning: Build your model, and use 2 stroke engines. Why? there were no 4 strokes or gas applications at the time.
Then gas engines appeared (Quadra) and the 4 strokes appeared later, and much later still RC Helicopters! That was something! Then ducted fan jets. Then electrics, much later electrics really took of with the brushless inrunners, and later outrunners. ARFs appeared. way before outrunners, etc.
To define "traditional RC" modeling w/o linking it to a date (like define rc tradicional modeling in 1965) is impossible. Like saying, OK, describe the physical appearance of a typical American male... Some threads are born to go nowhere, this is one:-)
My 3 cents
Gerry