Codeacademy doesn't overwhelm beginners with information. It gives bite-sized information, the bare minimum needed to finish a task and get to the next one. As the course progresses, it slowly fills in background information.
Codecademy is great for providing a hands-on approach, but there is a lack of context regarding how to start a project in real life. While users may learn how to code using Codecademy's interface, they may not have any idea how to code independently.
Rather than merely test for code correctness, Exercism uses peer review to improve general programming techniques. Users are encouraged to comment on others' solutions, and refine their own based on feedback.
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.