Stirrups. Zero. Shipping containers. Luggage with wheels. All these innovations seem obvious in hindsight. But they went undiscovered for millennia, until someone’s bright idea changed the world—or at least put airport porters out of work. Even those hotel shower rods that curve out made someone rich.

Fifth edition Dungeons & Dragons includes one obvious-in-hindsight innovation that Gary and the game’s other past designers failed to spot. Alas, it won’t make anyone rich.

Way back in my analysis of bounded accuracy, I explained how attackers in D&D Next tended to hit harder as they leveled up, rather than hitting more often. In “Changing the balance of power,” I wrote that fighters suffered from this new design. “The accuracy-for-damage trade matters most to fighters. Fireball and Blade Barrier work as well as ever. The rogue remains content to sneak up on the goblin king.” But if the Queen of Battle confronts a goblin horde, and she only makes one attack per turn, no amount of extra damage matters, because she can only fell one goblin per turn. “Fighter-types should hew through the rabble like grass until, bloodied and battle worn, they stand triumphant. Instead, they wind up muffing to-hit rolls against one mook.

“Earlier editions of the game offer a solution, a solution so odious that I hesitate to mention it. If fighters gain multiple attacks per round, the misses matter less because there’s more where that came from!”

Multiple attacks seemed bad because they always brought awkward memory demands and calculation. “D&D’s designers have struggled to parcel out extra attacks as fighters gain levels. Jumping from one attack directly to two results in a rather sudden leap in power. Instead, AD&D gave fighters extra half attacks, and a need to remember half attacks. Third edition traded half attacks and the memory issue for weaker attacks and fiddly attack penalties. Yuck.

“If D&D Next’s designers can find a good way to allow fighters to gain multiple attacks against weaker opponents, then a key piece of the Next design puzzle falls into place.”

Late in D&D Next’s creation, the designers compared the benefits each class gained as they leveled and noticed that wizards leap in power at 5th and at 11th levels. These jumps come from quirks of a spell list that dates to the beginning of the game. At 5th level, wizards gain potent attack spells like Fireball, plus unbalancing buffs like Haste. At 11th level, wizards gain 6th-level spells, which bring save-or-die effects like Disintegrate. At the 9th spell level, Gary Gygax felt comfortable stashing world-altering spells like Wish and Time Stop, because his players never reached 17th level and never gained free access to them.

Earlier editions of D&D aimed to parcel out benefits smoothly as characters leveled up. Those edition’s designers ignored the leaps in power certain spells brought; the fifth-edition designers embraced the leaps.

This brought the obvious-in-hindsight innovation: Rather than offering fighters half attacks or fiddly attack penalties, 5E matches the leaps in power brought by additional attacks to the leaps brought by 3rd, 6th, and 9th-level spells. Fighters gain extra attacks as wizards gain these spells. At the same levels, other classes make similar leaps, such as the rogue’s Uncanny Dodge ability.

Third and fourth editions arbitrarily aligned the game’s tiers with 10th and 20th levels, because of round numbers. Fifth edition aligns the game’s tiers with the leaps in power brought by 3rd, 6th, and 9th-level wizard spells. The designers finessed the other classes so they gain benefits to match the wizards’ gains.

It seems obvious now. Designer Mike Mearls says that a lot of innovations in game design work that way.