> Second, my email address also disappears. Third, all the IoT devices that use services on this domain become bricks. Basically, I disappear from the Internet.

While changing email is inconvenient, I don't understand the point about IoT devices. IoT devices should not depend on the Internet at all for obvious privacy and security reasons. If you are using IoT devices with "cloud" accounts, then this is a blessing in disguise. Put that garbage in the trash and rebuild around HomeAssistant, Zigbee, RTSP, etc. I find it hard to believe that someone hosting their own website would fall for the cloud IoT scam.

Plenty of people and businesses have their own (DIY, etc) devices that need to use DNS. I mean it wouldn't really be the internet of things, if it didn't actually use the internet...

For instance, I own a .house domain that I use for a bunch of stuff that I've programmed. It would be a pain in the ass to go change that domain out. Now take that to next level and you're a business that's deployed a few thousand devices that need to call home.

I guess all this is to say - IoT doesn't just mean cheap botnet honeypot IP cameras. Take a look at https://www.balena.io/cloud for instance

He didn't say his IoT devices relied on 'cloud' accounts. He said there are IoT that use services on this domain.

Imagine he's set up some IoT devices at his parents' home, and those devices use services that he hosts somewhere on the internet. It would be silly to hard code the IP addresses in there, right (unless he operates his own ASN)? So he would use DNS to allow those devices to find his server(s). This would be the case whether the servers are at his home, at his office, or in a rack at a data centre.

It sounds to me like you understand the point perfectly well, you just cared to make a different point.