All flowering plants gives fruits. Why does jasmine flower plant not yield fruits?
Flower gives rise to seeds and fruits which are the ways through them the plant distributes the seeds. 

Here, one should differentiate botanic term "fruit" and general common meaning of the word "fruit" which are not the same. 

Botanic fruit can be subtle, not fleshy and come as a grain or pods. 

Jasmine fruits are black berries.