Earlier quoted context omitted.
the problem is that nobody listened to Alan Kay and writes dynamic code the way they'd write static code but without the types. I always liked Rich Hickey's point, that you should program on the inside the way you program on the outside. Over the wire you don't rely on types and make sure the entire internet is in type check harmony, it's on you to verify what you get, and that was what Alan Kay thought objects shoul…
That's a terrible solution because then you need a bunch of extra parsing and validation code in every recipient object. This becomes impractical once the code base grows to a certain size and ultimately defeats any possible benefit that might have initially been gained with dynamic typing.
that's not a big deal, when we exchange generic information across networks we parse information all the time, in most use cases that's not an expensive operation. The gain is that this results in proper encapsulation, because the flipside of imposing meaning globally is that your entire codebase is one entangled ball, and as you scale a complex system, that tends to cost you more and more.
In the case of the OP where a program "breaks" and has to be recompiled every time some signature propagates through the entire system that is significant cost. Again if you think of a large scale computer network as an analog to a program, what costs more, parsing an input or rebooting and editing the entire system every time we add a field somewhere to a data structure, most consumers of that data don't care about?
this is how we got micro-services, which are nothing else but ways to introduce late binding and dynamism into static environments.