Indeed, and that's why Apple discourages the use of a contextual menu as the sole means to offer functionality as well [1]:
Always ensure that contextual menu items are also available as menu commands.
A contextual menu is hidden by default and a user might not know it exists, so it should never be the only way to access a command.
In particular, you want to avoid using a contextual menu as the only way to access an advanced or power-user feature.