I mean, why wouldn't xp tables be in something called "progression"?
Why have mechanics under core->mechanics and then also have a separate mechanics folder outside of that with more scripts? And that's not even the only example of that and not counting how a system could be dictated by things in multiple folders or scripts.
The short answer is, it's a programming thing. The long answer is, basically every event, person, something you can conceptually call a thing is an instantiation from a class or the like (Or "factory pattern" for those that took programming patterns in college). There's a fine line to what you want to define in the class statically and what you want defined to the instance. And that itself gets into code intuitive-ness, data security (not for hackers, but other classes or instantiations from polluting the class) and data mixing. And then, there's the "Let's just put it here for now. I'll find a better place for it later." that happens a lot when you're working on a significant sized code base. Some times, you just need a place to put some values and inside the the class definitions is the easiest way to do it
Would I have done it the same way? No. Is there anything wrong with doing it this way? Absolutely not. Up to a certain point, it's all subjective. And ultimately...
If it makes sense to Ron that's all that matters.
To
Karmadive 's point, I made a very, VERY similar point way back when (I think my line was "If the story is dependent on a certain level, tie the story to the level, not the level to the story"). Got so much heat and people jumping down my throat that my posts, among so many other's, were deleted. People swore up and down that the grind was good, not too slow and, if it was any faster, it would absolutely ruin the game... Then I made the cheat injector and the game's not ruined. I even got some lines like "That's just the way things are. You've just gotta accept it or play another game." My reply was...well, the cheat injector was born.
With that said,
I had considered breaking the level cap. But since the level didn't really do anything at the time, I opted to implement skill points instead.