They definitely don't need to get to the same place at the same time, and don't even need to end up at the same final destination. Some will go onto PhD program

They definitely don't need to get to the same place at the same time, and don't even need to end up at the same final destination. Some will go onto PhD programs, some will not, etc. Having two (or more) separate tracks allows the late starters a better chance at gaining competence without getting crushed by the competition with more experience.