I think part of it, also, is that a lot of peoples' exposure to relational databases is via MySQL and PHP, which is ... not representative.
Most people don't understand why the N-normal forms are significant, etc., because they learned SQL from a simple "how to save and load rows" kind of tutorial, rather than learning it from the big relational ideas outward. (I'm a "learn how it works as a whole" guy, but I recognize that most people aren't.) If you don't know why they matter, it just seems like a bunch of bizarre busywork, and then you get lousy performance.
I think part of it, also, is that a lot of peoples' exposure to relational databases is via MySQL and PHP, which is ... not representative.
Most people don't understand why the N-normal forms are significant, etc., because they learned SQL from a simple "how to save and load rows" kind of tutorial, rather than learning it from the big relational ideas outward. (I'm a "learn how it works as a whole" guy, but I recognize that most people aren't.) If you don't know why they matter, it just seems like a bunch of bizarre busywork, and then you get lousy performance.