I would say to give SAHMs of gifted toddlers a time to make doctor's appointments, get shopping done and maybe get a break to recharge? My kids gave up naps very early and were exhausting with their constant drive for knowledge.
Also, to give the kids a chance to meet friends and socialize and learn to be somewhat independent in a safe environment?
I know they worked on fine/gross motor skills and letters and numbers, which we could have and did do just as easily at home...but they also did fun crafts I might not be willing to mess my house up to do, involving lots of paint, shaving cream, water, etc.
