Please note that I did not say it was a graduate degree, I said it was a graduate program, which is what it is.
It is not a single class, it is a set of classes, with a core class, and a set of electives. A graduate program and a graduate degree are not the same thing. This is a graduate program.
Typically there are 3 tiers of graduate program by coursework (certificate, diploma, masters) and 2 tiers of graduate program by research (masters, Ph.D). Universities may offer none or all of these programs under different names.
There is sometimes another tier by coursework called a "diploma for graduates" which differs from a graduate diploma in that it is usually at the undergraduate level, and very occasionally you see a Ph.D by coursework.
Stanford also offers professional certificates through SCPD which are entirely distinct from their graduate program being targeted towards the continuing education market.
It is not a single class, it is a set of classes, with a core class, and a set of electives. A graduate program and a graduate degree are not the same thing. This is a graduate program.