The idea behind this plugin is related to Moodle sites hosted on cloud with variable usage patterns.
As we all know Moodle cron is by default configured to be executed every minute in order to provide correct backend
functionality to the system. In most cases cron actions directly depend on the presence of recent user activity. 
If there are none cron will still be executed but nothing worhtwile will happen. On self-hosted in-house instances that
may not matter much, but it does in commercial cloud environments where infrastructure is commodity and anything that 
can be billed is being billed.

If you desire to optimize your cloud provider costs it may be interesting to consider using this plugin.