[qsPerhaps you could explain how it is lacking? Are you saying that fitness is not a factor in the propagation of a genome?qs]
I argued aginst the use of the term fitness. Unfortunately, the term is well-entrenched in biology. I suggested that biology could be better expressed without it.
Here are the reasons I gave:
"Fitness of offspring" -- As offspring and/or their parents are, by definition "fit" simply by being there, then fitness is not a quality "of" offspring or their parents. As this is a grammatical, semantic point, then we can replace offspring and parents with any X. X can be genomes, for example.
As the OP appeared to select biological/chemical facts by using the framework of fitness, then it threatened his enterprise with a tautology. (Fitness can't be a quality "of" a life-form, or "of" X; if fitness is the presence of X. All we end up saying is that fitness is the name of X. )
(also note, if you argue that success of reproduction of the offspring makes them fit, then i) success of reproduction doesn't necessarily incur advantage to the species, and ii) clearly, if the offspring do not reproduce then the parents reproductive success cannot be regarded as "fitness" or success. )