I don't know whether to laugh, or to instead be triggered by the traumatic memories which were buried deep within the recesses of my mind until now and assume the fetal position.
This was originally done by IE way back in the day, for a variety of reasons - one being to not block IE. So, they just masqueraded the IE browser as Netscape. It's been a mess every since.
Yeah, it's one of those pernicious things that highlights that a powerful player like Microsoft can essentially lie or disregard standards for their own benefit and thus cheapen the entire purpose of the rule.