Faerun is a fake place built over years by one guy from his own campaign. WotC uses it as its default D&D setting and as such has to make it generic with many fantasy tropes. It’s going to be broken and lots of inconsistencies. Heck they pretty much tossed out the last 100 years because 4e bombed and they had to recon everything. The game dictates how the setting works which creates these problems. Look at the utter brokenness of the Warcraft story.
Which is my point, it's not a realistic or consistent fantasy setting. It is not even that original, considering they have initially borrowed from Tolkien and only backtracked on that because of a possible lawsuit.