It's only a misuse if you can show that it was used *originally* in a different manner. This is the argument used against "oxymoron." Supposedly "smart moron" was originally used to mean something completely different. Can this guy demonstrate that "steep learning curve" was ever used to mean easy and not hard? Looking at Webster's New Collegiate, the last and presumably most recent entry for steep is 4: "difficult to accept, meet, or perform." Clearly, this was the original meaning of the term. Why does this guy think it's wrong?