Why do we need tokens on Blockchain?

I think maybe you believe tokens are just cryptocurrency. Some tokens can be assigned a value and traded in markets but there are tokens that are meant to give the token holder rights. For example, a token might give you a share in a DAO (Decentralized Autonomous Organization). The share might give you a right to a certain percentage of profits or a right to have a certain vote weight. Another example would be after steemit's hardfork 20; resource credit tokens would give you such things as a right to use the tokens toward a discounted account creation.