Amazing that he went and spoke about a bunch of pointless crap before in the end actually stating exactly why so many tabletop RPGs, D&D or otherwise, don’t have authentic historical backgrounds. Because they’re just trying to play a fricking game, dumbass, of course!
Most of the RPG settings are actually based on books the game makers read, usually several put together. Particularly a lot of Lord of the Rings, Conan the Barbarian, and Elric of Melniboné as the three most popular were the inspirations behind the original D&D, or at least AD&D. (I’m not sure if D&D’s first ruleset was complex enough to really have much story support, I’ve always gotten the impression it was mostly just meant for dungeon crawl games, but haven’t actually sought out the original rulebook.)
And even since then, other sources have been added in (such as the aforementioned Kung Fu series, which frankly the monk kind of irritates me, because too many players/GMs treat every monk of every religion like they’re Shaolin.) Frankly, I would like to play a more historically authentic world myself, for a number of reasons. In fact, playing in a world much more like Medieval Europe could be quite fun, if you don’t have a Christian SJW GM who insists that there’s only one God with any power, and clerics of other Gods are just deluded and can’t actually use any spells because of it.
Also frankly, one of the best fantasy series I’ve ever read is more closely related to historical Medieval Europe, but not too much, and written by a man who appreciated that Tolkien was a devout Anglican Christian who, quote from The Rivan Codex, realized “pagans have more fun.” The Elenium books themselves are even actually the ones that kept me from losing all interest in reading as a child, and the Tamuli only continued my love for Eddings as a teenager.