[platz]

Well, speaking to the point of duality, I think Rx solves the problems it sets out to solve very nicely, and I would not say it has "design mistakes".

It certainly seems possible to use Rx primitives to build more functionality, yes.

Though everyone will have to build this themselves (if, of course, they even need it), and they'll probably all build it differently, where other lib's have this concept baked in (i.e. Pipes).

IMHO, libraries shouldn't try to do everything anyway, and to that end, Rx does it's thing and does it well (unix philosophy), as it's based on these mathematical abstractions.