Yeah, but many ISPs, especially smaller, have a same pool of ip addresses for all of their users in that 'region' (for whatever size and definition of a "region").
So with some effort, reconnections from/to a mobile network and many tcp/ip connectons, you can achieve that your device is connecting to the attacked site with many different (if not all) IP addresses from the ISPs pool, and if each of those is blocked, none of the legit users (using the same IP address pool) can access those services anymore.
Look at services like digitalocen with cheap virtual machines... even amazon... so many of their IP addresses were used for something "bad" and got blocked, that running a legit service on any of them can mean that a portion of your potential users won't be able to access them, because they'll be on some block list somewhere.
