Although natural hybridization is a valid path for creating a new species (
a completely man made concept) - one of the advantages that "True species" have over hybrids is that they were created through an evolutionary process in which they successfully adapted to fill a niche - a process that typically takes a long time.
Hybridization, otoh, is a quick process where you throw two groups of genes together and create a new entity that is typically somewhere between the two originals (depending on a number of factors on how the genes combine). So, by it's very nature, hybridization destroys (or modifies - if you prefer) the very unique traits that nature took so long to create via the process of evolution. MikeFallen13 stated this in a slightly different way:We recently learned that N. lowii's very unique shape (coupled with exudiate creation) is an incredible survival adaptation to capture nutrients from some of it's mammalian neighbors. When hybridized with another species it gives 'some' of those unique properties to it's progeny - but only some - so the original adaptation is destroyed (or modified) as it combines w/ traits from the other parent.
The same is true with N. aristolochioides. In offering some of it's unique traits to another Nep thru hybridization, it loses its incredible evolutionary trapping mechanism (or at least has it modified to be much less efficient). A similar structure, in a completely different CP group (Sarracenia psittacina) typically has it's fantastic trapping mechanism rendered completely non-functional through hybridization.
Each hybrid I have seen utilizing one of the 'toothy' species (N. hamata, N. villosa, N. edwardsiana, etc) loses most of that species incredible adaptation when paired with another species.