Oof, looking at this post made me realize that adding Attacker Diversity without also adding Catalyst Diversity would be a huge mistake. I know it wasn't the point of your post, but I kinda had a realization when looking at the screenshots and thinking about how the last few rifts I have fought have been.
Setting aside the part about duplicate supports (like SG and Sketchy); The two fighters shown in the screenshots here, Silent Kill and Summer Salt, are both buff removers, and very good ones too. In most rift matches, I end up using my buff removers to counter buff catalysts like Darknut or Frost Armor, since it's pretty much guaranteed to see one or both of them in every match. Whenever I have to reuse a buff-remover, 9 times out of 10 it's to counter a dupe catalyst.
If there was an Attacker Diversity requirement but not a Catalyst Diversity one, people could make Rifts that were impossible to full score simply by spamming Frost Armor on every node because there simply aren't enough easily-obtainable buff-removers for people to use a different one on every node. This would be neither fun nor interesting, and would make dupe Catalyst spam a much bigger issue than it is now.
On the other hand, adding in Catalyst Diversity without also adding Attacker Diversity would lead to a lot of folks having weaker bases then they do currently, which might lead to other issues regarding the 'optimization' of scores by spamming dupe supports, rather than having to figure out specific counter strategies or thinking up multiple ways to defeat the same defense node. (Tbh, I haven't had to face much dupe fighter spam in rift yet, so I'm having a hard time thinking of specific examples, but I don't think this would be as big of an issue as the first one.)
Basically, one without the other would make the dupe spam an even bigger problem than it is now, so Attacker and Catalyst Diversity bonuses need to be added in at the same time, since they balance each other out in a way. One incentivizes varied offensive strategies while the other incentivizes varied defensive strategies. They would lead to a more fun and varied experience overall, but only if they're added together.
Not against catalyst diversity.
Touched on it on @Dusty00's thread - https://forum.skullgirlsmobile.com/threads/rift-attacker-diversity.15954/#post-39627 .
Reason for not going into it here is as stated :
Not talking about catalyst spam as dynamic modifiers might affect it.
In a stall modifier, catalyst diversity is definitely needed.
Not sure for dynamic modifiers though. Have to test it firsthand before saying anything conclusive. Surgeon and couple other variants can be abused on most stall and dynamic modifiers.