A good SO flow is just one of the signals that will get you noticed (amongst others such as a high gpa, open-source contributions, certifications, etc). Most probably it will just get you the interview. After that, its all upto your performance during the 5-6 hour onsite interview and coding solutions on the whiteboard to complex algorithm problems (atleast at the top tech companies). While SO does discuss algorithms and data structures, there is no guarantee that every SO user with a 5 digit score knows or would do well in a high-pressure whiteboard coding interview.