Why is SAP PPM more than a task tracker — what are its main benefits?

It incorporates international standards (e.g. QS-9000) and methods like the automotive APQP; supports NPDI (new product development & introduction), professional-services delivery, internal IT projects, Six Sigma.

Benefits: a single source of truth for company-wide project transparency; planning/structuring/scheduling/execution/control; role-based responsibilities; approval-protected phase gates; web collaboration; resource management; predefined templates to shorten time-to-market; status dashboards/alert governance.