Speaking as someone who worked for an ISP and looked after our DNS and domain name registration infrastructure (amongst many other things) lots of folks and for

Speaking as someone who worked for an ISP and looked after our DNS and domain name registration infrastructure (amongst many other things) lots of folks and for all sorts of different reasons. It's not as uncommon as you might think. And the extra diagnostic steps described in that article (or similar) were daily drivers when debugging customer support issues related to DNS.