That aspect was rather unique among the dmm games I've seen on Nutaku, entirely due to deployment cost being a thing.

The 99% of Aigis being doable by gold units would be on Nutaku side, right? IIRC, majin advents are known to be on the 'Blacks or get the hell out of here' side of things (understandable, as it's high end player content). We just never got them before it closed.
Likewise, majority of the stuff we have here are doable with SRs and below. Mainly, the events with missable rewards, as those are meant to be cleared by the general populace. The things that basically ask for SSRs are endgame content. (and then there's tower quest, which asks for quantity)