One of them actually recently looked into building their own solution. However, they realized, that in order to create something really valuable, you need at least a couple of months of dedicated engineering efforts of people who really understand GraphQL.
Our automatic and powerful cache invalidation - currently only possible with Fastly, a whole GraphQL-specific Analytics solution and a Security suite is nothing you can quickly clone.
Anyone of course can, but you need a highly GraphQL-specific product with many workflows like CLI workflows to upload your GraphQL Schema etc - it requires quite a bit of thinking and engineering to make that work.