DDOS attacks still happen because they are still effective at causing companies problems, at their core their abusing the fact that the internet is there to transport data, and their data. the cloud flare incident that’s is being mentioned was google interposing its network and throttling the attack traffic, they got it before it could ramp up, interposed, throttled instead of deny, and managed to mitigate the attacks impact ont he servers, however that process would have still cuase issues for some users, just not the majority of them. Such stuff is also expensive, as someone is now tying up part of a network and the support to interpose, filter, and then passing good traffic.
No im not a network engineer, im not a systems security person, none of that, but a couple of things, you can flood traffic, and force either steps to be taken, that then still have some impact on end users, even if its just extra latency and delay, and force the company to pay to mitigate the attack, or if they have their own means divert resources to it, or they aren’t going to be able to mitigate it either fully, or at all, and their going to go down. Either way you are causing the company problems and costing them money, which is the point of a DDOS, its to cuase the company its targeted at a problem.
and why do they still happen, because they work at the task of causing the company a problem, the reason, it could be cover for a hack, it could be a script kiddie renting bot nbet time, it could be hackers, who knows, but it cuases the company issues, so they get used. the core principle is simple, even if the attack types change from junk data to pings, to bad server call requests, to what have you to try and get around various protections aginst it. As the defenses evolve, so has the exact method of ddos, and so has the sheer volume of data thats getting thrown around.
You can ask what defenses blizzard has, why they dont have more, or do more, or any number of other things sure, but understand, ddos still happens becuase it still works at its core, and that core is it cuases the company problems.
as a extra that AWS amazon attack, the compnay i worked for had switched to AWS for phones and such, that attack even with amazon working on it took us out, spotty when it was working, and just down alot, love getting paid for sitting in a chair, but thats money amazon was loosing.