Why did Apollo allow Phaethon to ride the chariot?

Apollo allowed Phaethon to ride the chariot to fulfill a promise he made to his son, demonstrating his paternal love and desire to support Phaethon's wish to prove his divine heritage. Despite knowing the dangers of the chariot, Apollo wanted to give Phaethon a chance to experience his celestial legacy. Unfortunately, Phaethon's lack of skill and experience led to disastrous consequences, highlighting the importance of understanding one's limitations.