>>96024658Other games usually stick to one rule system for their "magic" as it limits the need for a game to ask how do these two different types of magic mechanically interact with each other. If you've every actually paid attention you should notice that games tend to use a general "magic" system (if fantasy) or a more specialized "psychics/psionics" system if more sci-fi.
D&D and its descendants/clones (such as Palladium's Rifts) are some of the few games that have tried (and for the most part failed) to properly include both a general magic systems and a psionic system at the same time. This lead to a bunch of different rules for how these distinct systems interacted until the devs decided to give up and just include psionics in the base magic system rather than try to make it anything distinct.
The actual biggest success stories for settings and games that both include separate magic and psionic systems has involved isolating users of each system from each other. Dark Sun made using Arcane magic taboo and Divine magic (mostly) impossible and so Psionics was the primary "magic" system of the setting. Psionics in Eberron were pretty much locked to their own sub-setting.