I suspect most DMs simply handwave it that the faux-Chinese in their settings never invented gunpowder, for whatever reason, and leave it at that.
Okay...but do notice the implied double standard here. The real world--and its real technologies and real cultures--are supposed to be used as the basis for what does or doesn't happen. IRL history matters....right up until the point where the GM decides "nope, doesn't matter, that thing doesn't happen in this world". Which makes any argument built on "well this is how it worked IRL so it's how it should work in this fantasy world"
inherently suspect.
If this is the tack we choose to take, that the GM may simply handwave real historical developments when those things are inconvenient for that GM's preferred tone, style, etc., then what we're talking about isn't realism or verisimilitude or even groundedness anymore. It's now an elective choice to project a
specific style--which means appeals to realism aren't valid for justifying it anymore. It would be like appealing to "tradition" for why one uses real oxtail or real beef tendon in a Cantonese dish (which, to be clear, I find properly cooked beef tendon
delicious, so this isn't a knock against traditional Chinese cooking!)...only to then say "I substituted cabbage instead of bok choy because I wasn't really feeling bok choy today."
To assert that one
must do X thing because it is historical, only to then knowingly and intentionally break from history simply because history didn't suit you with thing Y, makes it look like that previous appeal to history was a disingenuous guise to justify, even reify, one's purely-subjective preferences. That calls into question whether history actually
matters, or whether it is a convenient excuse only invoked to dismiss criticism, not as an actually principled rationale.
One could argue, given the prevalence of monsters and threats in a typical D&D setting that our own history never had to deal with, that such technological innovation never gets much of a chance to take root because those who might do it are too busy dealing with those threats instead.
Or one could argue that the constant threat of dangerous enemies--many of which can use magic--would mean that gunpowder, which was known for at least a century in China before they discovered it could be weaponized, would get weaponized a hell of a lot
faster. Harder for mister fancy-pants wizard to mess up your day when you can fling as many "fireballs" as your alchemists can brew, while they're limited by daily spell slots.
Threats can absolutely delay progress or cause knowledge to be lost. (Take your pick of the crises that plagued Rome from like 250 AD onward, for example.) But threats can also massively
accelerate progress, if they induce significant innovation in order to survive a threat. When considering an entire planet's worth of regions and cultures and conflicts, it seems unlikely that
none of them would experience the acceleration effect.
That, and in a D&D setting "academia" is largely replaced and-or supplanted by "magical studies"; the brightest minds tend to either go into magic or adventuring, or both. Which means, it's more likely that a new spell will be invented to solve [generic problem x] than a new technology, with the side effect of keeping that solution gated behind the ability to cast spells and thus exclusive to the casters - who can then profit from it as they like.
Not necessarily. Every society still needs lawyers and physicians and architects. Magic is certainly tempting. I don't think it's SO tempting as to totally displace everything else.
Because if it were, by that standard, every smart person IRL would become a computer programmer or industrial engineer, and that very clearly doesn't happen.
Magic for the masses is the main thing that makes Eberron an atypical setting.
Sure, but by that same token, it's also a kind of "low-magic" setting! Because
powerful mages are extraordinarily rare, but
weak mages are quite common. Almost the reverse of the typical (allegedly) "low-magic" setting, where mages of all stripes are rare, but ultra-powerful ones seem to be confusingly common relative to the number of mages overall.
Think on it: in your own game, once they get to half-decent levels consider:
--- how often do the PCs engage in long-range travel?
--- how far do they go?
--- what are their means of getting there (and-or back)?
In order, at least for my world (which, like yours, is not 5e):
Regularly, because while teleportation circles exist, they're expensive and legally required to be registered with (local) government. If you use a clandestine one, you're risking steep fines (because taxing teleportation is a major source of government revenue). If you use a public one, you're risking people knowing exactly where you are at all times. If you use a private but registered one, you're trusting that person...and probably paying out the nose for a registered but untaxed private circle. Assuming that there even
is a circle close to where you want to be!
Somewhere on the order of 100-ish miles outside of the closest
major city, and depending on the exact location, ~50 miles away from the nearest settlement. The Tarrakhuna is an arid-to-desert region, so settlements can be few and far between, while the interesting locations are often far away from anywhere truly livable.
Usually, camelback, but sometimes they spend the coin for something fancier. The party does have one magical statuette that summons a warhorse shaped from magical energy, but it's got limited use before it needs to recharge, so it's mostly useful for "and back" if they have stuff to carry.
Your own setting might be different, but in a typical setting there will be other adventuring types doing similar travels, never mind mages and clerics who may well (and it's not unreasonable to think they would) have set up globe-spanning teleport or planeshift networks for their own use.
Even if they do, such things are terribly expensive and out of reach for most people....and usually require either
familiarity with the destination, or an entrenched circle.
Plane shift is an extremely powerful spell; it takes a world like the Forgotten Realms, which is absolutely
gonzo in terms of how many powerful mages it has, for more than a tiny handful of people to be able to use such a thing, and even then, only a very limited number of times per day--plus rare, expensive, and difficult-to-acquire ingredients.
In my own game,
plane shift isn't a spell. It may once have been, but it isn't now. There are only and exactly two planes known to be accessible to mortals other than the planet they live on (which in the local tongue is called Al-Duniyyah, lit. "that which is near" or "the place of examination".) Those are Al-Akirah, the elemental otherworld where Jinnistan is located amongst other things, and Ja'hannam, also known as Hell. The Safiqi priesthood (primary religion of this region) claims the existence of other planes as well (at the very least Jannah, "true heaven"), but no reputable planar research has ever demonstrated that any other such plane exists.
The party actually does know that
many other planes exist, they've even specifically visited one, the artificial "perpendicular" plane of Zerzura--but other than that one plane, which was EXTREMELY dangerous until they rolled in, no other planes are
accessible from their planet, because it's trapped behind some kind of barrier which prevents departure outward to other planes besides Al-Akirah. Their world is a
prison for something powerful that really, REALLY wants to get out, but they don't know why yet.
End result: long-range travel would be considerably more common among the elite than in our own history, and often stupendously faster.
But that's the keyword:
among the elite. Keep in mind, for most of human history, "the elite" was a very, very small proportion of the population. Even with the horrible income inequality we currently deal with, it's still a bigger proportion of all people than was ever the case in medieval times.
Local problems and concerns are much more immediate for the common folk, sure, and as they make up the vast majority of the population your point is valid. Elites and adventurers (who tend to make themselves elites pretty fast even if they didn't start out that way) would likely take a different view; and as play revolves around the particular adventurers that happen to have players attached, that "elite" view is what we as DMs find ourselves having to deal with.
I don't think the conflation between elites and adventurers is valid.
Sometimes that will occur. It will depend on the characteristics of the setting. The thing is, most of the stuff the elites want isn't going to be interesting to adventurers. They want things like nice, stable, lucrative trade routes, cash crops, and (for the more bellicose) logistic advantages. Adventurers generally want to be going to places that are isolated, forbidding, and far away from most settled places...because if these dungeons etc. were
close to settled places, they would have either destroyed those settlements, or the settlements would have destroyed and/or looted them, simply because they are mutually hostile.
Some adventurers will retire and, in so doing, tend to become elites. But many will not, because we play weirdos who don't really fit into the humdrum stability of ordinary life, even elite-rich ordinary life. Those who do not retire will often desire to go to ever-farther destinations, ever-harsher environments, ever-grander threats--because the thrill of the adventure (and, for some, the good their efforts can do) will be almost as valuable as the coin they get from it.
