The quote that follows is from SRG after they investigated an airprox I am aware of. (It might not be word for word but that changes nothing in its' essentials.) Traffic was passed on a/c VFR, the other under radar vectors IFR, class D. TCAS saved the day when nobody flying the planes got visual with anyone else. "The controller did exactly what the book says he should do. But we don't want them doing it like that...…" There, Gentlemen, is the problem.