I think the biggest adoption stopper would be that building a dependency chain (like say a JSON parser) could already be quite many functions. As the end user you don’t care about the architecture of JSON, you just want to consume it and get an object. In the end you might virtually end up with libraries again, because in some sense abstractions over functions are libraries. There’d still be a win though because if you store the execution AST in a common database you can provide consistently tested primitives over many languages… However I think outside of functional programming circles no one really actually cares enough about this to tackle it