Just recently I had a server go through a 10Gbit DDOS (likely more - since my total bandwidth to that server is 10Gbit) - the provider (Linode) got in touch with me about it and managed to mitigate it but unlike a home service:

- I pay them to assist with mitigation.
- I wasn't hosting anything to make anyone angry.
- the attackers were targeting several Linodes, not just mine.

The attack was also coming from thousands of IP addresses (a large scale botnet)

It makes total sense for a home provider to block the target IP and talk to the person who owns that connection. If providers mitigated it without any (negative) action towards the customer who may have been doing something dodgy then the ISP has to follow up regardless - but some DDOS's normally stop if the end IP stops responding (if done by script kiddies).

I am all for my ISP blocking my IP if I get attacked. If they simply moved it to another IP who knows, my Linux ISO's I'm seeding may well be making somebody angry and they target my new IP instead.