Jerricho
I spend about half my airborne time VFR in class D airspace. ATC prevent the type of conflict you refer to by not allowing me to start my base leg until I have visual contact with any IFR traffic on the final approach. They have no need to actively separate the traffic.
If the VFR traffic does not provide sufficient separation in the opinion of an IFR pilot I know damned well where the **** goes, because I know someone who has been filed against very recently. It is not toward the controller.
Bright (surely a misnomer?) Ling
If you bother to read C&B's post it is obvious that someone was not allowed into the circuit at a class-D airfield and was given the reason that ATC could not provide separation they were not required to provide. For a flight instructor this is frustrating - remember you get paid to train and get paid whatever the traffic you work. We pay for our training, only get paid when we are airborne. You have come across here as sneering, arrogant and completely unconcerned about the issues other people face or about their skills and knowledge.