240.21(B) says conductors may be tapped to a "feeder".
The article 100 defines a "feeder" as all circuit conductors between the source and the final branch overcurrent device.
No where in the definition of feeder does it ever specifically mention either main or feeder circuit overcurrent devices, but we know these devices must exist (see 215.3). So breakers are either considered 'conductors' or they are ignored when defining feeder circuits.
As far as UL and breaker manufacturers go, they clearly allow 'taps' directly from circuit breakers as there are Listed power distribution lugs for many industrial breakers (typically up to 6 #14-4AWG openings).
