I'm aware, I also host various websites that see an IP do a single request to the most unlikely of deep pages. Usually not hard to correlate with similar surprising requests from the same ISP, though, and that's exactly why it would be useful to talk to them: they know who used that IP address at the given timestamp. If they get a hundred complaints from different websites, the ISP is in the unique position to correlate that and find the subscriber(s) that are problematic

You also don't have to send out 1k support requests per hour. Could trial it with some hosting provider that you expect is responsive and see how it works out

edit: like, I just don't see another solution short of banning being anonymous online. Each site would have to know who you are. Someone has to be able to track it back to a person that is doing the abuse or there can't be any rules that we can apply. Imo it's better if that's the ISP (or VPN provider, say) who already has this information anyway