There is a fundamental difference in scale between MMO and RPG.

MMO's argument for online portions of their service were based around that scale. There are plenty of online only games, loot boxes, microtransactions that can happen outside of MMO/RPG style games, some existed before MMO's even took off.

To ignore the fact that MMO's absolutely do need more hardware and need to be split between client and server shows a clear lack of understanding or knowledge about client-server models, large multiplayer games and development.