That's because with the traditional publishing model, it was, "I will give you money for a finished product."
With crowdfunding, it's "I will give you money to finish a product."
Kickstarter is for people who, for whatever reason, have not capitalized their project. Maybe they couldn't secure financing, maybe their business model is garbage, maybe their product is unworkable, maybe they are clueless on how a product gets to market. Whatever the reason, you are the source of capital investment.
Want to be an investor? Use Kickstarter.
Want to buy an actual product that actually exists? Use Amazon.
Kickstarter is not a store.