Many questions about Drupal don't have a "correct" answer. More often than not when I ask questions of those more experienced than me about an issue with Drupal in person, their answer starts off with, "it depends".
A lot of the questions asked on Drupal Answers require detailed knowledge of the poster's site architecture and substantial background on the problem in order to give a definitive best answer. By comparison, questions on Stack Overflow are typically limited to a far narrower scope.
I feel that many of those who answer in the comments want to assist, but feel more comfortable providing their thoughts in the comments. This allows them to provide direction to the asker while recognizing that their guidance is more of a push in the right direction than a canonical answer.