For me it's all just silly and everyone just has to handwave it. After all... as I've mentioned before in other threads, by the same silliness token we are still stuck in these pseudo-medieval worlds despite having powerful "D&D" magic that has been around for millennia and yet has never seemed to produced technological advances with any of it.
In our real world the transistor was invented around 1947, and now in less than a century our world took that technology and evolved it to where it is right now-- with all the advancements humanity now experiences with it (education, transportation, medicine, communication, food etc. etc.). And yet we're supposed to believe in places like Faerun... a place where the "Age of Humanity" has been in existence for almost 4,500 years (let alone the tens of thousands of years the elves and dwarves ruled prior to that)... no one has been able to use the "technology" of magic up through 9th level spells was able to provide to get them past horses and castles? Just how stupid are all these people? And just how economically unsavvy are they that not a single person has been able to take the miracles of what magic could provide and actually advance the world with it? A single person could literally
Fabricate whatever they could think of upwards of 3 times per day with the right materials and yet not a single enterprising entrepreneur ever learned about mass production and the evolution of construction to get us past wagons? Really? They've had the miracles of 9 levels of D&D magic for thousands of years and yet have remained completely stagnant with it... yet we "normies" in the real world just by using our brains have gone from the tech level of the Ancient Greeks 2000 years ago to where we are now by actually evolving our tech and our world.
So with that absolute silliness and illogical thinking of so-called "world-building" being a highlight of just how ridiculous all D&D worlds are... I've just ignored it from the very beginning for the sake of "playing the game". We players want to play in fantasy medieval fiction with knights and magic, so D&D worlds remain in perpetual medieval stasis to allow us to do so... and the true effects of powerful magic that D&D allows for us to have for gameplaying sake just never seem to do anything permanent to a civilization and instead are all just whitewashed over in order to accomplish it.