to save for a down payment. This is a tool to profit on kids who want to buy more than they can afford. They literally can't afford it but want it any way. So a company comes in charges a high fee like a high interest rate to save them.
And if it is for people who can't save enough, your example doesn't work. How can someone who can't save enough all of sudden have enough in 2 years to buy the home?
Once again, I don't see this as useful tool for the vast majority of people. If invested in this, I would get out fast because it won't last long IMO.