Not quite: the paywalled standard itself contains bits like "dot or comma" for fractional part separators, which are then interpreted differently. Some software would use a dot (for printing and/or parsing), some would use comma, some would depend on a locale. It also allows to omit time zone (making the time unclear) and is generally quite complex, with implementations being incomplete (or having subtle differences) sometimes. Of course it's better than the zoo of formats, but RFC 3339 (ISO 8601's profile) is considerably better for interoperability, eliminating ambiguities and many options.
Not quite: the paywalled standard itself contains bits like "dot or comma" for fractional part separators, which are then interpreted differently. Some software would use a dot (for printing and/or parsing), some would use comma, some would depend on a locale. It also allows to omit time zone (making the time unclear) and is generally quite complex, with implementations being incomplete (or having subtle differences) sometimes. Of course it's better than the zoo of formats, but RFC 3339 (ISO 8601's profile) is considerably better for interoperability, eliminating ambiguities and many options.