The main reason 'take home' assignments are BS: It will take the qualified person that needs to evaluate the submitted result more time to go through the code you produced and make a basic judgement, than it would take that same person sitting in a room together with the candidate to produce a far better judgement of the skills by just talking with the candidate if front of an IDE.

Truth is many of these 'assignments' will never be looked at by a person that can actually derive good insights from the submitted work. Most of the superficial treatment they will receive could have been established in a five minute phone interview.