“Known IP addresses” to me implies an infrequently changing list of large datacenter ranges. Maintaining a dynamic list (along with any metadata required for throttling purposes) of individual IPs is a different undertaking with higher level of effort.

Of course, if you don’t care about affecting genuine users then it is much simpler. One could say it’s collateral damage and show a message suggesting to boycott companies and/or business practices that prompted these measures.