I must admit, I am not good at starting new discussions. I just participate the others' discssions. However, I find it good way to practise my writing and I like to do discussion more that entry. 

To hear different opinions from others around the globe. 

  1   To teach English

  2   To teach thinking in English

  3  To educate in general

   4  To acknowledge the effort of the student who sees some assurance.

   5  To operate with  an ethical   function,   opposing those who would use the

forum to endorse violence, or  intolerance,  the suppression of any gender, ethnicity, or nationality.

If you ask me, the purpose should be that while discussing something, you would discover what you already can and especially cannot express in a certain language and then one would ask a question about that or one would be corrected.

Nevertheless, ... it unfortunately often goes into useless chit chat, proselytizing ones opinion and political and religious preaching. You can especially see a few people here repeatedly posting in discussions, without making notebook entries or asking questions. In my humble opinion , if they then are not interesting in learning a language, they should go to a debate forum, or post on their facebook wall.

I really would encourage people who post in discussions for other reasons than learning a language to bogger off to another forum!