The most likely explanation is a user unfamiliar with DNS tried to configure the DNS records and made a mistake that's glaringly obvious to anyone familiar with DNS, but not to people who aren't.
While a DNS label can be any arbitary binary data generally, you should read the rest of section 11, in particular:
Note however, that the various applications that make use of DNS data
can have restrictions imposed on what particular values are
acceptable in their environment. For example, that any binary label
can have an MX record does not imply that any binary name can be used
as the host part of an e-mail address. Clients of the DNS can impose
whatever restrictions are appropriate to their circumstances on the
values they use as keys for DNS lookup requests, and on the values
returned by the DNS. If the client has such restrictions, it is
solely responsible for validating the data from the DNS to ensure
that it conforms before it makes any use of that data.
Among other things, this means that the label syntax may be constrained depending on the RR type. As specified in RFC 1123 section 2.1 and RFC 952, Internet host names have such a constrained syntax, in which the colon and slash are not valid.
https://www.example.com
is different from the the IP address mapping forwww.example.com
. The former maps to addresses (multiple A records) in the /16 netblock owned by "example.com" per ARIN whois. The latter maps to a CNAME in the domain of a major CDN provider. The CNAME chain ultimately maps to an IP address in the CDN provider's network