Frontlefthamster
ATC will provide a service if it suits them. Any tinpot GA putt-putt plane flying through the climb out lane, the approach lane, or the overhead deserves attention, if for nothing more than to divert them around station based traffic. But realistically its so that reduced separation minima can be applied to the necessary degree. Any GA tinpot putt-putt plane that doesn't come within the above parameters is in essence a pest, and will receive an appropriate amount of attention in accordance with its type of service only. Sad but true.
Aiming at traffic is a fantastic way to 'avoid' confliction under certain conditions. These being dependent on speed, agility, type of transit, and type of service of the platinum pilot/plane combo. If any are lesser than the eejit being avoided a climb or descent is the best way to deal with the situation, unless of course you are in radio contact with said eejit.
If Mr Tinpot is VFR and Mr platinum isn't tough ****!