Why do you think women and men joined the Sangha?
The men and women probably went to the Sanghas due to the following reasons:
1. They wanted to attain enlightenment, by staying away from worldly activities.
2. They could deeply study the Buddhist philosophy by staying in the Sanghas.
3. Many people entered the Sanghas to become teachers of dhamma.
4. They also joined so as to free themselves from social constraints because after joining the Sanghas they were not known by their social name but from the name they get when entering the sanghas.