Flawed logic. The first thing they tell you in systems analysis is that bad money is bad money and throwing good money after it won't change that fact.
Bad money is throwing away LV after LV to fill a leaky Depot. That's throwing away good money after bad. Price per pound of payload doesn't change that fact. All an HLLVs hydrogen gets instantly used. Price per pound isn't the only think to look out. Shroud diameter is another plus SLS has over Falcon.
Of course, the EELVS could, and for the most part they have. Mainly because they operate on a smaller scale, spreading experience and technical knowledge over a higher flight rate allows them to make developmental improvements a few at a time and evolve their capabilities into new technologies.
SLS uses D-IV as an insertion stage in that it is a payload for SLS and thus its reach becomes greater. Not either or--both/and
A man on Augustine who trashed HLVs, gave us the Roton.
A man on Augustine who supported HLVs is still beating his wife.
See, I can do that too.
Anyone who kept up with greason knows his Roton is a joke. Griffin wrote an AIAA textbook on spacecraft design.