Have you ever found yourself needing to use the same element on many different pages over your site? a site alert? a spoiler alert? a newsletter signup? a banner of any kind?
This is what shortcode templates allows you to do. Create as many different templates as you like with whatever content you need and then insert them anywhere on your site using a shortcode. If at some point in the future the content of that template needs to change simply edit the template and all instances where it’s used will automatically change too.
Shortcode templates can be useful for different notices you might need/want to display in some articles of your site, such as spoiler alerts or adult content alerts, or it can even be used to display custom or third-party advertisements without having to edit every page where they show up every time you need to change a banner.
At the end of the day the goal of shortcode templates is to make your life easier and save you time so that you can spend it doing the things that really matter!