Why is Zion destroyed for another to be built

Why does Zion need to be destroyed if another is just going to be made? I don't understand why the machines would come to wipe out Zion, and then have 23 ppl rebuild it to later destroy it. Is it because the ppl of Zion know what's going on and can creat problems to the condition of the Matrix?

Basically, the original 23 people become 2300 and eventually 23,000,000 which would eventually pose a bit of a problem for the machines....so they just cut them off at the legs....and get 23 fresh and new unsuspecting naive slaves