I think it's quite excusable in Russian novels, since that seems to be the natural way people address(ed?) each other in different contexts in Russian culture. A fantasy novel has little excuse though.
I'm the author of the posted article, and I am currently reading Brian Sanderson's latest Stormlight novel and suffering from character/name overload (doesn't help that I read the previous book years ago).
I also spent many years in Russia, where I noticed that they have few names (just a dozen or so common ones for each sex) but a gazillion variations, depending on context (e.g. family, friends, work). My theory is that under Stalin, you didn't want to stick out, and a boring name like Natalya Ivanovna was less likely to be noticed and remembered. Your trusted friends could have some unique nickname for you, like Natulya. But I never read War & Peace--it sounds like the naming practice predates Stalin. My Russian daughter is currently reading the book, so I'll have to discuss it with her.
I also spent many years in Russia, where I noticed that they have few names (just a dozen or so common ones for each sex) but a gazillion variations, depending on context (e.g. family, friends, work). My theory is that under Stalin, you didn't want to stick out, and a boring name like Natalya Ivanovna was less likely to be noticed and remembered. Your trusted friends could have some unique nickname for you, like Natulya. But I never read War & Peace--it sounds like the naming practice predates Stalin. My Russian daughter is currently reading the book, so I'll have to discuss it with her.