I fully understand that. Same is true for inflation theory. It was concocted to explain away several major problems with the big bang. However, as far as theories of their existence and workings, it is certainly worth a try to treat the hypothetical pair as though they were similar in nature to their very real counterparts.
Until it can be proven that 'dark matter' and 'dark energy' even exist, there's little point in going through that exercise. It will only lead to the invention of some other goblins or fairies, that likewise exist in theory only.
Ultimately, such exercises are destructive, as they produce ideas which further solidify the existing cosmological paradigm, which itself, is an enormous conglomeration of unproven, untested, unworkable theoretical constructs, that does nothing to accurately predict or explain observed phenomena in our universe.