a tyre off the ground cannot transmit any force...so deliberatly lifting wheels is sacrifyce 25% of available grip ! Anyone in racing should be prepared to kill when offered as ecret to gain an instant 25 %of available grip for a given situation...
It´s not that easy in real world:
I had more than once situations when completely unloading the inner wheel would actually help the situation of available grip..So in general the first principle applies:
use what you have to the max
but if the circumstances demand try things to make it workable -it is a compromise after all.-at least at the track when you cannot develop a new car in two 30minute sessions..
I don´t see the relation to negative camber though ... but i see a relation to anti ackerman ,providing more lateral grip with less steering lock(= lower slipangle ) at low loads(not true for all tyres methinks).
I always think this could possibly cause unpleasant steering input (going straight ) when you find a bump or high spot with the inside wheel (= load transfer caused by road irregularities).