Not only that, but it's extraordinarily capable as a graphing app (and comes with examples demonstrating its features), too! It also has a pretty crazy history: https://news.ycombinator.com/item?id=1584501
The current macOS Grapher app is an unrelated replacement for that Graphing Calculator app, which Apple no longer has a deal to distribute.
Interesting, I had no idea that Grapher existed. Looks like it is only the spiritual successor to the classic MacOS Graphing Calculator, not an actual continuation by the original developers: https://en.wikipedia.org/wiki/Grapher