Periodically, somebody will bring up one of Gironda's routines that resembles the classic HST template. Somebody could do a search here and find that example discussed pro and con.
I'd say, though, that layoffs has been a standard part of periodization thinking since the 80s, and most experienced trainers incorporate that as a matter of course into the training. What Bryan did was introduce a unique, very specific context to the application of a "non-active period." SD, RBE, and progressive load are the three legs which supports HST's strain theory.
The controversy over SD's "uniqueness" is also a reflection of the disagreement over whether this theory really should be distinguished from the progressive overload model that drives strength training. Most skeptics of HST don't think it should. Because they do not recognize the otherness of a hypertrophy-specific language/paradigm from their strength-specific model, they presume HST is a variant of other well-established programs and that the terminology has only rhetorical import.
I think it's a valid objection because you could certainly describe a HST program and its rule set to somebody else with periodization principles. In fact, many of argued HST is the classic "single-factor" hypertrophy program.
But, then again, there are lot of tweaking recs that make no sense from a strength-specific point of view. That is, there are elements of HST which cannot easily coexist in a true strength training program. And it also holds true that there are lements of strength training, which may not happily coexist in a hypertrophy oriented program. Seeing, then the imposition of one layer upon the other is the key to understanding their practical differences . . . as well as seeing the method behind all workout design.
But, yeah, DOMS is the most important thing in the universe. It is the philosophy that which cannot be explained by science. Amen.
cheers,
Jules