It is a failure of visual separation in Class G airspace... ATC don't have eyes on the back of their heads, and separation of VFR traffic is not their job.
People are completely forgetting about the limitations of unalerted see-and-avoid here. If there was no limitation, we don't need a controller. They are there to help prevent collisions.
This is achieved by passing traffic information and/or applying separation.
For controllers to pass instructions to pilots, while 1) giving pilots the freedom to ignore those instructions, and 2) giving themselves the freedom not to pass any traffic information, and 3) giving themselves the freedom not to provide any separation - the three points all being possible as it is uncontrolled airspace, and THEN expecting that pilots should know about each other and exactly where to look out for each other, is an accident which has already happened.
This is because pilots perceive controllers to be in the know about the bigger picture, else they wouldn't have given them instructions.
Posters here are correct that a pilot in VMC is ultimately responsible for their own separation. However I go back to my original point which is that inappropriate airspace classification, in this case the fact the airspace is "uncontrolled", should not be used as a liability waiver.