over the years, imdb ratings have gotten worse and worse. this is due to more access by younger/stupider people. so you have to look at other factors. one easy example is that superhero films are ALWAYS overrated, often by a lot. people are just in need for good ones, so when something decent comes along, they cream everywhere over it

TWD is the only zombie thing on TV and it's somewhat watchable, therefore everybody loves it. If it wasn't about zombies or post-apoc, but instead something like a high school drama, it wouldn't have gotten past 3 episodes