Didn't Xeno famously have to swap off WAR to GNB for his group to clear week 1? I remember his group being stuck and then the moment he swapped off WAR his group was able to clear door boss. So it's not like week 1 groups had 0 difficulties, I know a few people that ran into similar issues and had to swap their dps or tanks to different jobs.

If I had to guess, PF is used as a representation of the game because a lot of people do content through PF. And while weaker jobs have for sure cleared the tier, this is actually the first time in recent memory that RDM has had such low numbers. It has a less than 20% use rate vs the other 2 casters on every fight except for P8S part 2. Even when it was relatively weak in Eden tier 1 it still had more representation than this tier. RDM is the most popular caster in the game and has been since it was introduced in SB, for it to have such low representation this tier it's clearly not just PF excluding the job and not people just assuming it's in a bad spot based on PF. RDM is underperforming and it just doesn't have enough ways to keep uptime on such a movement heavy tier.