[mooted1]

Have you ever worked in a polyglot ecosystem with rapidly evolving schemas?

Tools like protobuf and thrift were designed to facilitate schema evolution since interfaces in these ecosystems evolve quickly and independently. Generics undermine this by creating strict dependencies on a few types, making it difficult to evolve a single type without breaking things.

Poorly implemented generics would undermine one of the design goals of this project. In addition, there aren't nearly as many opportunities for generics in an IDL as in a programming language, so what would the upside even be?