Go read the NSF mission statement and then come back and explain how it limits the scope of the agency to doing science.

The NSF's focus areas do include research on people and society, as well as development of new training and education initiatives (https://www.nsf.gov/focus-areas/education) and fostering a robust STEM workforce (https://www.nsf.gov/focus-areas/workforce). Not every grant issued by the NSF needs to be geared towards fundamental scientific research; the NSF's mission is broad, and intentionally so.