You encountered 2 problems and neither of them was the take home assignment. The first is that the company ghosted you. That is unacceptable regardless of what

You encountered 2 problems and neither of them was the take home assignment. The first is that the company ghosted you. That is unacceptable regardless of what your hiring filter is. You’d be just as aggravated if they’d brought you in for 6 hours of interviews and then ghosted you. The second is they didn’t set expectations (or at least you didn’t tell us if they did). Should you have spent 6 hours on this? How long does it normally take? After the assignment would you be brought in for 6 more hours of interviews or is the assignment the major filter? At the end of the day, take home assignments are the best filter, the most equitable and the most efficient way to do hiring consideration. Companies (usually the middle managers within them) just don’t have the courage to use them correctly and don’t spend the resources to make them a good filter (they also don’t spend resources on the other job filters so those aren’t good either).