Before they were invented early players used soccer balls
James Naismith called Spalding and asked them to make a ball specifically for the sport the result was a leather ball held together by laces and was 4 inches bigger than a soccer ball
Over the years basketballs have went from basically balls of leather to being specialized for certain uses
For instance an indoor basketball is made of full grain leather and is usually very slippery when first used and requires breaking in
An outdoor ball is made of rubber and is basically broken in already and is usually ready to use right out of the packaging
Theres also indoor/outdoor ball hybrids which are usually a combination of of the two materials and have enhanced grip so they can preform adequately in the gym and outside
Think about this for a minute how many times have you just dribbled a ball because its fun
Now picture this you picking up a soccer ball instead
Now imagine this your a ball player and your teams not so good and the soccer team has practice when you have a game now you have to forfeit a game having two separate things is a way better alternative