The Giraph/Pregel model is based on bulk synchronous parallel computing,
where the programmer is abstracted from the details of how the
parallelization occurs (infrastructure does this for you). Additionally
the APIs are built for graph-processing. Since the computing model is
well defined
In principle you could implement (and it has been) Pregel through MPI. The
idea behind Pregel was precisely to factor out typical patterns of graph
processing that used to be based on message-passing and barriers. A
framework like Pregel/Giraph hides this complexity through a well-defined
API and