No need to legitimize what is actually going on here, my web server doesn't scan the entire internet just because multiple computers might want to connect to it - it sits there absolutely silent, just waiting for someone to connect to it on port 80 or 443. A 'smart' vacuum cleaner could trivially listen for a network broadcast sent from a controlling device like a phone or PC, and then reply with whatever IP address and port it's listening on. This can all work seamlessly over DHCP with no need for ping or port scans at all. Lets be real though, this is not what corporations want. They want to displace traditional appliances and devices with remote intelligence gathering platforms that they can use to enrich their bank accounts long term with subscriptions for services, up-sells, fingerprinting, and advertising. If they are lucky, a secret 3 letter agency might even pay them an absurd amount of money for 'unrelated' reasons.

You might think I'm being a little bit cynical here and I wouldn't blame you :-) For quite a few years I was employed by the Defence Signals Directorate, and that was after a long stint in the Navy doing tactical electronic warfare.

VLAN and firewall your stuff, if it doesn't work without internet, you don't need it.