Poor English is the biggest obstacle of learning on bitcointalk. It makes us unable to express well and make the article poor quality.
That's not necessarily true.
There are "local" boards designed for users who speak/read/write in languages other than English. (I believe these boards even have "merit sources") So, there is no reason why you cannot participate (assuming there is a local board for a language you are fluent in), even if your English is "poor".
But it does not make my text smoother and the reader does not understand my implication.