Quote from SilverWolf_27 »The timescale problem happens pretty much everywhere. Given the level of technology in the Silmarillion, Sauron should just get nuked from orbit in LoTR. It all boils down to creating a cohesive and recognisable world even across long timescales - if you take realistic technological development into account, you might as well be creating a different setting altogether. Similarly, if past Tarkir was radically different from present, it might as well not be called Tarkir at all.
I always go with the "magic inhibits technological advancement" argument. Its most directly addressed in the Harry Potter universe so I'll use it as an example. Basically, the existence of magic makes technological advancement much less likely, because people tend to take the easiest path when solving problems, and magic is the easiest path. Magic lets you warp reality to your needs or desires. Sometimes it takes a lot of training, sometimes it relies on innate ability, but either way magic users have an amazing advantage over people trying to solve problems with ingenuity and invention. Because magic is about warping the rules of nature, people don't bother studying the rules of nature, because why learn how the world works when you can change it instead? That's why the wizards in Harry Potter are pretty backwards when it comes to technology despite the muggle world advancing as normal. The problem with magic is that it only solves the immediate problem and you don't learn anything from it. In the real world, knowledge gained from solving a problem helps solve other problems, and technological advancement has a snowball effect. The more we learn, the better equipped we are to learn more. The more we create, the easier it is to create more. So you create a sensing spell to detect enemy wizards, and your left with a sensing spell, but you create radar to detect enemy planes, and you have something that can be further developed and applied across fields.