In reply to John.

Classic editor is the official plugin for removing Gutenberg, and the install count is apparently being used as a metric to gauge success of the Gutenberg project. So, although other plugins exist to force-disable Gutenberg, using them doesn't properly notify the core team of the number of issues users are having, that's why Classic Editor Addon doesn't disable Gutenberg itself, it just properly sets the options for Classic Editor and disables the Gutenberg Nag notice, making it easier to mass-install classic editor.