Why would Discontinuous Conduction Mode be desirable for an LED driver?
A SMPS in DCM will not give lighting strobe effect.  


  Discontinuous Conduction Mode is an operational mode of a switching power supply in which the current starts and returns to zero.  


This applies to the current through the inductor/transformer, not to the current through the load.
The load current will have a non-zero mean value.

EDIT: additional clarification
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Another 'proof' DCM will not give lighting strobe effect: check the grey shaded features of this driver in led-professional.com


  Target Applications:
  •    Flicker-free LED driver for indoor or outdoor applications


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The IC supports so to say two SMPS, the PFC and the flyback. The following applies:


DCM in the PFC stage (power stage) is to support light load
conditions and ensure efficient operation.
DCM in the flyback is to support light load conditions and ensure efficient operation.


So, DCM is used in both SMPS for exactly the same reason.


  Depending on the actual situation, the built-in digital control (of the flyback converter)  selects the best mode of operation. It can switch between



QRM: quasi-resonant (when e.g. 100 LED's are connected)
DCM: discontinuous conduction (when e.g. 10 LED's are connected)
ABM: active burst modes. (when e.g. 1 LED is connected)


(Number of LED's is illustrative of course)  

Why would Discontinuous Conduction Mode be desirable for an LED driver?
To have freedom to connect 1 LED one time and 100 LED's the other time, using the same LED driver having high efficiency for every type of load.