I was asked to support my statement that you were not allowed to "daisy chain" fixtures together using factory whips. This is my justification of that position.
We are required to have all the wire in a circuit meet the ampacity of the circuit; the ampacity is defined as the size of the breaker. This is particularly relevant here, as 210.23(B) allows a lighting circuit to be as large as 30 amps.
We're also allowed to use the fixture itself as a raceway (even without it being marked as such) when connecting strings of lights. This is discussed in 410.64 and 410.65. It's worth noting that these wires passing through the fixture are referred to as 'branch circuit' conductors.
Because that's where the issue hangs: just where does the branch circuit end, and the listed (410.6) fixture begin?
I submit that, as a matter of definition, any wire supplying more than one fixture is still part of the branch circuit, and thus has to comply with branch circuit ampacity rules. Kiss that #19 whip good-bye. Tap rules can't apply, as there is no over-current device at the other end of the whip.
402.10 and 402.11 address the use of fixture wires as branch circuit conductors. I believe that these two sections, when combined, are an attempt to address this point. You can use the fixture's wires to supply that fixture, but not other fixtures.
I will concede one might encounter a similar situation using Reloc, or other factory-made wiring system. In those instances, though, the system is listed as a whole, and I believe it is acceptable as long as the directions are followed.