Indeed I fully agree that for reproducible research to have the source code is the most important thing. I’ve never said otherwise. 
As mentioned before by @oxinabox there is always a need for source code and I second that.
Please let me explain what I meant under relevancy though.
My workflow is very simple and straight forward:
raw experimental data processing -> data to work with
Once all work is done on code I’m able to apply same “black box” (version controlled) on any data from my experiment.
That “black box” contains all possible outside packages dependencies at the time the source code was properly tested and finalized. This will assure that if there is some breaking update on any package it will not break the workflow.
Executable is a snapshot of the code that can be indeed further deployed and distributed to other colleagues that are not as skilled in compiling the code.
Definitely not a blocking 1.0 feature.