Isn't the result of this class of solutions a service on the web that can _only_ (easily) be accessed by the client code that was specifically written to use th

Isn't the result of this class of solutions a service on the web that can _only_ (easily) be accessed by the client code that was specifically written to use that service (by virtue of being built out of the same lump)? Doesn't that kill one of the best aspects of the web: client independence?