Obryn
Hero
You have got to be kidding me.Because someone vaguely remembered reading fiction by this guy Jack Vance and was trying to broaden the number of influences used in D&D. It's fundamentally a sim element, not in the sense that magic is real but in the sense that it's trying to create a genre-specific experience in the world that is paralleled by the mechanics.
It's a tangential part of balance at best. Again, resources only matter if you run out of them, and even if that happens, the spread of outcomes it creates is pretty unappealing. A typical D&D spellcaster is not going to run out of useful spells before he gets the chance to rest and recover them.
It's much more important to think in terms of odds of success, opportunity cost, risk, and other in-world tactical considerations.
D&D is an intentionally balanced game, and even if you're going to try and assert it's a Vance simulation (it's not), its role as a balancing factor is undeniable.