Why the Patristic Reports About the Heresies Shouldn't be Taken that Seriously

I wonder if anyone else has noticed that there is something lacking from the reports about 'heresies' in the Church Fathers.  They all seem so one-dimensional.  In fact, the 'heresiological works' of the ante-Nicene period as being based on Irenaeus's original report from the Commodian period (c. 177 - 191 CE). 

Irenaeus wrote something, maybe many things against the heresies.  Photius characterizes these early works as 'lectures.'  But whatever the case a five volume book ends up being published called 'Against Heresies' whose first book is represents the earliest surivivng catalogue of the various 'species' of gnostics. 

I stress the word 'gnostic' here because the original of title of the work seems to classify all the heresies as being actively involved in the dissemination and promotion of 'false knowledge.'  The corollary of Irenaeus's argument is that has received 'true knowledge' and it is now preserved in the Roman Church. 

The Roman Church can't always have been in possession of this true knowledge because its bishop - Anicetus - challenged the authority of Polycarp.  Irenaeus clearly believes that Polycarp is the source of the 'truth' about Christianity.  When the tradition of Polycarp was reconciled with the Roman episcopacy, 'truth' could properly be said to have resided in the capitol. 

Irenaeus certainly claimed that he got his understanding of what 'heresy' was from Polycarp.  Yet Irenaeus seems to be the first person to have established what 'heresy' was and what 'types' of heretics there really were out there. 

There is of course a reference in a heavily edited letter of Justin to the Emperor Antoninus Pius which makes reference to a 'syntagma' (treatise) against the heresies.  But it seems hard for me to believe that Justin would have included this in his original letter.

Beyond this however, it is important to see that it is only Irenaeus's words which frame the most important heresies especially with regards to 'the Valentinians.'  Indeed does anyone really add anything to the discussion about what a Valentinian really is?  Well, Tertullian does say something - he reports that those who are identified as Valentinians deny that there ever was a Valentinus. 

It seems to me that Irenaeus established the categories which later Church Fathers used to 'pin labels' on brethten of questionable faith.  Yet I have strong doubts about the accuracy of this original categorization.  I don't think it was a precursor to Charles Darwin's Origin of the Species ...