Online Shopping and eCommerce
If you have a busy eCommerce website, you know that the last thing you want is a crashed site. Having a popular product for an online sale can bring its own problems, with payment systems, inventory systems or your site search going down when you have too many people trying to buy at the same time. If your buyers know that a product is going on sale at a particular time, and will sell out, then people arriving just before it goes on sale hit refresh, refresh, refresh to be the first to buy.
You only need a few hundred people doing this to bring down even larger websites. When your servers are down, this downtime harms the reputation of your brand, let alone the lost sales and the damage this does to your bottom line.