Further down they also mention that the requests come from CFs ASN and are branded with identifying headers, so third party filters could easily block them too if they're so inclined. Seems reasonable enough.
We're creating an internet that is becoming self-reinforcing for those who already have power and harder for anyone else. As crawling becomes difficult and expensive, only those with previously collected datasets get to play. I certainly understand individual sites wanting to limit access, but it seems unlikely that they're limiting access to the big players - and maybe even helping them since others won't be able to compete as well.
I'm split between: Yes! At last something to get CF protected sites! And: Uh! Now the internet is successfully centralized.