There are, to put it bluntly, a lot of ESL textbooks for adult learners that are, to varying degrees, crap. There are many and varied reasons why these books are awful. Many of them are weighed down under more than one layer of language guano. You're waist-deep before you even get started, digging through the stink to find something useful.
I know what the rationale behind it was, and understand that many Koreans really think that sort of stuff is spiffy, and are drawn to shop somewhere that shows that kind of rigorous employee-indoctrination methodology, but it was still deeply, excitingly Weird.