It's quite standard these days. If you're already with Akamai then you're not an attractive target though, so maybe that's why you haven't seen many of those? The DDoS services are really cheap today and it's pretty normal to get attacked regularly if you're large enough. For $100 you can easily get 5gbps for a few days, or larger volume / shorter time for <$50 subscription. But there's no reason to attack anyone already on a quality CDN service.

> and I don't think people should default to trying to prevent them.

It's the usual instance calculation - how much will you lose if you're down for a day vs how much would you pay per month. Some people will not care, some will happily pay tens of thousands.

Then there's business specific stuff. It would extremely hurt a florist to go offline for a week before Valentine's Day. (If they take online reservations)