Below are the key reasons why most people fail to achieve a high score in the IELTS writing section:

1. They don't answer the question properly.

2. If they do answer the question properly, their answer lacks unity meaning that they go off topic.

3. The paragraphs lack structure or enough development.

4. Their grammar and vocabulary is too simple.

5. Their grammar and vocabulary have too many errors.

6. Their answer does not provide a clear answer, meaning that it is difficult for the evaluator to identify their position.