One starts to wonder, at what point might it be actually feasible to do it the other way around, by whitelisting IP ranges. I could see this happening as a community effort, similar to adblocker list curation etc.
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Source: stopping attacks that involve thousands of IPs at my work.
My single-layer thought process:
If they're knowingly running a residential proxy then they'll likely know "the cost of doing business". If they're unknowingly running a residential proxy then blocking them might be a good way for them to find out they're unknowingly running a residential proxy and get their systems deloused.
And what if I'm behind CGNAT? You will block my entire ISP or city all in one go, and get complaints from a lot of people.
Alas, the "enough users get annoyed by being blocked and switch ISPs" step will never happen. Most users only care about the big web properties, and those have the resources to absorb such crawler traffic so they won't get in on the ISP-blocking scheme.
You can be completely forgiven if you're speaking from a non-US perspective, but this made me laugh pretty hard -- in this country we usually have a maximum of one broadband ISP available from any one address.
A small fraction of a few of the most populous, mostly East-coast, cities, have fiber and a highly asymmetrical DOCSIS cable option. The rest of the country generally has the cable option (if suburban or higher density) and possibly a complete joke of ADSL (like 6-12Mbps down).
There is nearly zero competition, most customers can choose to either keep their current ISP or switch to something with far worse speed/bandwidth caps/latency, such as cellular internet, or satellite.