Yeah that's why when people claim something i now ask them to source or link it or i discard it under 'i swear bro'.
So you're now suggestion that they have new base classes? well welcome to the original point that they haven't been adding them, and it also takes you back to your issue what about people with jobs that had no class but now do? do they get exp for those new classes? the answer is yes obviously and there is no issue with that. Different is now in your suggestion they would have to make a class for each job instead of having the current existing jobs and classes available.
The same reason it works now what do you mean, we currently are using the Class system right now there is no difference other then more choice after you level to 30 your class you can choose more jobs i didn't invent the class system.