The System as world-building premise
The System in LitRPG is not just a mechanical interface — it is a premise with world-building implications that extend to every social institution, relationship, and political structure in the world. A world where power is quantified and displayed, where anyone can see their own capabilities as numbers, where leveling is a real phenomenon that some people achieve and others do not — this world is fundamentally different from ours or from conventional fantasy, and the most compelling LitRPG fiction draws out those implications rather than treating the System as a backdrop to a conventional fantasy story with stat windows added.