Li Shenron
Legend
We're going to give A5E a spin once my books come in, but it's been a reality at my table that every paladin player has saved their spell slots for smiting. I can't recall the last time one actually used anything from their list.
You should meet my current paladin player. Dude almost refuses to use smite.
You two together just explained why smiting and spells are pooled together into the same resource in 5e: some players like spellcasting Paladins and others not so much. While technically you can't NOT have spells slots, you can choose to use all your slots for smites (there's at least 1 for each level) and practically work as a spell-less paladin.
A similar case could be thought for the Ranger based on Hunter's Mark, the mobility spells and maybe some of the Conjure, but it's harder to pull it off, as some details and descriptions of those spells go a bit too far in the supernatural to narrate them as less than magic.