Unlike many code practice websites, Exercism requires the user to develop and test entirely offline, submitting only the finished code. This promotes familiarity with essential tools and workflow, not just the bare language.
It's best to have at least a basic understanding of programming before tackling the exercises on exercism.io. You also have to know how to set up your development environment, as you will be coding everything locally (versus websites that provide you an editor right in the browser).
TreeHouse provides a a forum for students to have discussions. However almost all posts are students looking for answers to the quizzes and challenges. Any attempts at general discussions about business, learning, programming, job seeking etc. tend to go without replies.