For Kincaid, hes does that with superior use of equipment and ambush(of course, a few centuries of active combat experience helps here, as does superhuman senses and endurance), in a universe where wizards have known weaknesses(range, running water, empowered circles). Basically, he just proves that with time and prep you can take anyone.
Mostly, the wizard's running out of resources is a significant concern in almost every setting but D&D, where he'd have enough left to go depopulate a few towns before he needs a nap. But then most of them are closer to point pool systems, and on top of that, magical fatigue bleeds over to physical fatigue for many.
So D&D has these weaknesses removed:
-Repertoire size - see absurd number of combat spells known compared to majority of fictional casters. The total spells known may just barely be matched by a POWERFUL caster's combined combat and ritual magic lore.
-Endurance - High level power is distinct from low level power, whereas in many fictions casters conserve their big guns because using one could wear them out and leave them unable to light a candle, or in extreme cases leave them weakened for several days after.
-Convenience - No need for unique, personalized foci, no need to bother about stellar/planar alignment, circumstances of the casting, ritual clothing, magic circles and diagrams(though to be fair this last is often bypassed by action casters, whether with pre drawn runes(cards/paper/clothes), imagined circles, or using illusion/energy control to Instant some up.
-Speed - By far the the biggest gap. For most casters in fiction, only simple, practiced effects are combat speed, and for even powerful casters, raising an effect to begin with(discounting working with a precast effect, as is often the case with polymorph, telekinesis and flight) would take a few rounds worth of time. Of course, each spellcaster has their favorites which work with fire and forget speeds, but these are usually only just acceptable compared to their maximum output. Big or exceptionally nasty spells require more time to put together, especially for weaker magi.
Missed any?