"As built" would be a great place for newbies to start. Problem is that nobody wants to stay there for long. Most people get "the itch" after a year or maybe two. Next thing you know, its M&W kits, hitches, and tires. A couple more years, its strokers and race fuel.
Tractors evolve. Drivers evolve. Competition evolves. Its just part of any motorsport. People naturally want to improve themselves and by extension, their rides.
Its hard to get new people started without a bone stock class, but its hard to have a bone stock class because nobody wants to stay there.
Catch 22, so to speak.