The popular idea that astrology is mainly predictive is unfortunate. Those who have a nature to take advantage use astrology in this manner...again, unfortunate.
In ancient times, the natal chart was non-existent. No one went to an astrologer to find out about themselves. Natal astrology is a fairly new aspect of astrology and even this is not focused on prediction.
I think where people tend to get confused is when they assume that 'potential' means 'prediction'.
It is the potential that is seen in a natal chart that can help guide us. From our natal charts we can see where our strengths and weaknesses are.
Astrology does not say 'can't do this' because the planets are not properly placed. We can do anything- however, how much effort and attention that will be needed is found in the natal.
One who has a lot of Earth placements will usually be a natural business person but lack some emotional softness.
This does not mean that they cannot be compassionate or that they will have a CEO position handed to them.
Potential and inclination, knowing these things as seen in a persons natal chart is what is helpful and can be of use in improving our lives.