PHP is a great example of the convergence of interfaces. Now they have different “PSR” standards for all sorts of things. There is one for HTTP clients, formatting, cache interfaces, etc. As long as your library implements the spec, it will work with everything else and then library authors are free to experiment on the implementation and contribute huge changes to the entire ecosystem when they find a performance breakthrough.

Types seem like a “feature” of mature software. You don’t need to use them all the time, but for the people stuck on legacy systems, having the type system as a tool in their belt can help to reduce business complexity and risk as the platform continues to age because tooling can be built to assert and test code with fewer external dependencies.