NMIMS School of Business Management, Mumbai

You can get your answer for "why not PGPM" as follows:
PGDM VS MBA:
The curriculum of MBA course is more inclined towards offering theoretical knowledge while PGDM programs offer students with greater industrial exposure.
MBA programs lags behind PGDM programs in terms of adapting and adopting. The curriculum of MBA programs largely depends on university while PGDM programs being offered by autonomous body/institute design its own curriculum and thus enjoys the flexibility to constantly update the curriculum as per industry requirements through its industry-integrated approach.
The curriculum of MBA programs along with teaching methodologies are not updated as per industry requirements. However PGDM programs meet industry requirements. Thus students possessing PGDM degrees are more likely to grab hot job opportunities with the essential experience and knowledge. Hence PGDM programs offers fast-paced career growth as compared to MBA programs and turns out to be the intelligent choice between the two.
PGDM vs PGPM
PGDM and PGPM are two different courses. PGPM is an award program and not a degree; and is not an AICTE recognized course. It is not offered by an AICTE approved institution and a student who pursues a PGPM will not qualify for higher studies like PhD since PGPM is an award program and not a degree. A PGPM Course may be of any duration and is offered at the Institute level; whereas PGDM courses are of 2-years duration. They are designed by integrating current management theories with industry specific perspective and allow students to go for higher studies.