(granted I have grafted, I am playing devils advocate)
All techniques in gardening can be useful in some way given your understanding of it and its applicability to what your doing when, etc. etc.
HOWEVER: When something is not a "new" technique discovered recently, and still remains uncommon, it raises question. Why might this technique not be a popular idea in cannabis cultivation even given the numbers limitations. Plant number limitations have been a consideration since the medical marijuana era and long before 1996...
I will let others speak first, however would like to point out a simple and obvious reason this lacks in applicability across the board. (each strain requires various nutrients essentially at different ratios and times etc. making no host plant perfect for hosting a multitude of varying strains)