Well maybe you are right! But i started with a native japanese sensei and i doesn't necounter any problem. But what work for me might not be the same for everybody!
If you want to advance to a reasonably high level, there is no doubt that you would eventually require a native speaker as your teacher (if you didn't start with one). Listening and interacting with native speakers help with the finer nuances of learning the language. e.g., natural sounding pronunciation, better sentence construction, the cultural aspects of language etc. Equally important however, is *immersion*. I can't stress that enough. Internalizing a language can only come if one speaks and listens enough of it and that is difficult to achieve inside a class room environment. Having japanese /japanese -speaking friends help as it provides an outlet for language practice. Failing that, there's always anime and manga to fall back on
