[bruce511]

>> And you'd have to be incompetent if you have access to set DNS records and you set them to RFC 1918 addresses.

Clearly the following is not in play for a root domain (Microsoft.com) but assigning a DNS entry to a class C address does have a purpose.

If you have an intranet server, giving it a DNS name allows for HTTPS serving, with an automatic, CA signed, certificate. (Using say LE with DNS challenge.)

I provide this simply as an example of how this might come about.