One of the most common ways to get an event notification is by email. So what happens when you get 500 emails in a day and only one or two are actionable? Do you read every single email? Spending quite literally hours to find those one or two gems? Or do you just ignore the whole lot and wait for some other notification that there is a problem. Say, by a user calling you?
Next, let’s say you have a job that runs every few minutes checking if an instance is down. When that instance goes down you get an immediate email. Which is awesome! Of course then while you are trying to fix the issue you get dozens more emails about the same outage. That is at best distracting and at worst makes it take longer for you to fix the issue.
Fun story time: at one point during my work career, there was a person (not me!) who accidentally broke every single SQL Agent job on dozens of instances and nobody noticed it for hours. These weren’t production instances so it wasn’t the end of the world or anything…except that included in the broken jobs were a bunch which ran every minute. And alerted every minute. Via e-mail. The entire database team essentially lost e-mail access for 3 days as there were so many messages coming in that it overwhelmed our provider’s ability to serve messages to us. This type of mistake can happen, and if we had put into place some of the things Kenneth talks about, the consequences would have been less severe.