While it doesn't seem entirely unreasonable, I can't help but feel it's the state we're at. A platform having to trawl the web to find links to its own service,

While it doesn't seem entirely unreasonable, I can't help but feel it's the state we're at. A platform having to trawl the web to find links to its own service, infiltrate itself, verify the contents, then shut it down... I suspect a marginally easier way might be to maintain a list of referrer URLs/joining IPs (or start collecting them) and check them against a list of domains/IPs of sites known for sharing CP. I'm also not sure to what extent the onus should be on WhatsApp to try and remove this stuff, in the same way that I'm not sure to what extent the onus is on Google to trawl through Gmail inboxes it finds through crawling child porn sharing sites - the latter idea seems ridiculous to me, but maybe it's just because of the scale of the platform or the issue, but with a lack of hard data made available as to the extent of WhatsApp being used for CP, I think it's better to remain skeptical. But I will add this: if (and it's a very big "if") it is determined that it is right (in whatever sense we can use the word) to stop people using the platform in this way, I would never consider "but it costs money to do that" to be a reason against doing it in most cases. Justice doesn't stop because it's expensive.