But why is prisma a copy of graph-cool? I mean.. everything but the console / login

The main difference is, that graphcool offers resolver functions that you can deploy alongside the database on the graphcool cloud. Prisma is only a wrapper around the database and exposes only CRUD operations through a graphql interface. It’s not supposed to be queried directly from the client but from another server that hostes your businesslogiv and implemtens your custom resolvers. You can implement such a server with graphql-yoga.