Snippets going away?

I finally got around to checking out the snippets lab feature, but I can't get it to work. I created a snippet item, but it doesn't get replaced even in something like Notes that I'd expect to be well-supported. Also, the Google Docs file:

https://docs.google.com/document/d/1TjWdarf3XH_0vQWpU40Gv0Jk5_Gm49LGYjRDlP6svzQ/edit

that's linked from the Settings window pane as documentation has been deleted.