system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5:Why isn't there a good defense for companies against DDOS attacks?

As someone who plays Blizzard games, I found myself locked out tonight as a result of DDoS attacks. This was most likely because Blizzard issued a ban wave against cheaters and hackers.
But this seems like a recurrent problem for various companies.
If it's so common, what is it about a DDoS attack that makes it so hard to defend against?
Also, keep in mind, I'm not a hacker nerd, I really do need you to explain it like I'm 5, but someone who grew up in the 70s who is 5, not someone who is 5 in 2016.
Thanks!
gpt
DDoS means Distributed Denial of Service attack. Now you obviously experienced the part where service was denied. The key here is that it was distributed. 

What that means was rather than one guys with his one machine trying to keep their service too busy, the attackers used a great number of compromised system that all worked together to keep the service too busy. Because they are using so many separate machines to attack, there's no commonality they can use to filter them out early, because each of those machines start by connecting and pretending to be potential real customers. But processing them all through this process just overwhelms the system before they can identify the bad guys from the good guys.

As a metaphor, imagine there is an old school pizza store taking calls for delivery. A speaker at a local conference tells his audience who are staying at hotels all over the city to call this one store and go through the process of ordering a pizza, only to wait right until they are going to take a credit card number and then say, "oh never mind" and hang up. Suddenly the pizza shop is incredibly busy trying to take orders and all their resources, including phone lines and people taking orders are super busy. But for the most part it is fake orders. Legitimate customers might occasionally get through, but mostly they get a busy signal because all their lines are busy. Even most people trying to place fake orders usually get a busy signal.

It's kind of like that, only with internet servers being the pizza shop and potentially tens or hundreds of thousands of fake callers.