Flynn's taxonomy, and "task parallelism and data parallelism"
Task/Data parallelism is a simple classification that lies at the algorithm-level of a computation.

Flynn's taxonomy describes low-level machine architectures or models.

Trying to draw lines between both completely ignores the vast sea of complexity that lies between those two levels.  Using an example; You can do task, data and pipeline parallelism perfectly on a SISD for example. Stating that you cannot ignores the vast complexity of today's operating systems.