If date and time components are ordered from least precise to most
precise, then a useful property is achieved. Assuming that the time
zones of the dates and times are the same (e.g., all in UTC),
expressed using the same string (e.g., all “Z” or all “+00:00”), and
all times have the same number of fractional second digits, then the
date and time strings may be sorted as strings (e.g., using the
strcmp() function in C) and a time-ordered sequence will result.
We can debate this all day. And I can’t honestly say that I would take either side in a purely semantics argument.
But the wording comes directly from RFC3339 which is, to me, the definitive source for useful date representation.
https://www.ietf.org/rfc/rfc3339.txt