All the NZQA assessments are aimed at trying to find a NZ qualification that the foreign one submitted is roughly equivalent to, to let INZ see how the applicant fits in to their requirements.
What PAR does is just to give a possible level, going purely by the name the qualifications are given in your home country. Since obviously there are big differences possible in terminology, even from one English-speaking country to another, it is notoriously hit-and-miss.
On the other hand, IQA asks for your certificates, AND details of the course you followed, AND related work experience, and looks at what you studied, for how long, to what depth. Therefore, they are then able to give a proper assessment of your qualification - what level it is at, and also, it is to be hoped, a NZ qualification, if one exists, that yours is nearest equivalent to.
I quite agree, the IQA is what you need now. You're not the only person, from many different careers, to feel that PAR is a waste of their time.