They're not just "web pages". They're a key part of the financial infrastructure sustaining the problem that Cloudflare gets paid $600m/year to fight.
Does that imply that Cloudflare is intentionally boosting the problem? No. But let's be clear here: anything that makes DDOS attacks less of a problem means less money for Cloudflare. So whatever their intent, Cloudflare is helping to support the problem that they owe their existence to. It's very much a conflict of interest.
That doesn't sound very plausible to me. Your theory is that there are criminal gangs sophisticated enough to create large DDOS attacks but so clueless that won't use a cheap virtual server and a VPN when setting up their public intake?
And even if it worked for Cloudflare, it's not like they're shutting down the DDOS services they're tracking. The services could still go out and attack non-Cloudflare customers. So even if you were right, it wouldn't be exculpatory.
Does that imply that Cloudflare is intentionally boosting the problem? No. But let's be clear here: anything that makes DDOS attacks less of a problem means less money for Cloudflare. So whatever their intent, Cloudflare is helping to support the problem that they owe their existence to. It's very much a conflict of interest.