Why not tell why the block RAC

The name of the notification often does not fully explain the meaning, the trigger time has some confusion; RAC because of the binding of specific instances, the meaning is clear, but there will be a time to trigger the problem, the relative advantage is the first time to execute

Block will callback output binding, RAC will input event binding; in other words, one is self-triggering because the binding is output of the fruit (one to the other), the input is the result of binding from the trigger (a pair of more, in fact, KVO is so), RAC more friendly point; KVO API binding is cumbersome

Why not tell why the block RAC