Or maybe you are missing the point completely? You're talking about situations where leaden salute doesn't shine. If you don't want to take the effort to make it good that's completely on you. But it's fairly easy to pair yourself along with that geo to make it great. There aren't that many situations where it just wont work at all just might require a bit more work to make it work. As far as accuracy goes you aren't that far behind a rng and with new gear coming up you can get a ton more acc than before. And no you are very rarely competing with every other slot. The whm doesn't compete with the sam.
Except you are giving buffs AND dding AND debuffing AND enhancing debuffs so you can't straight up compare dmgs. And as far as buffs go... outside of scherzo they are about as game changing as anything brd brings. Idris Geo is a little too OP for anyone to compete with now but in my experience as you like to say so much geo +cor > geo +brd. And incursion isn't the only event so not sure why that keeps getting brought up as a litmus. And just because your pt brings brds instead doesn't mean there are no better alternatives. :p. Quite frankly every situation is different and it's completely impossible to balance out every job so that every job in every situation is "able to contribute as much as another job "
So your cor isn't the greatest at 1 event oh no that's why the game has different events and job change. I mean what the all the other DDs that you completely ignore? The fact that you aren't even mentioning any of them suggests that they aren't able to contribute as much as the dds you are using. Or that cor is in fact contributing as much as them therefore contributing as much as another job just not the jobs you chose to pick to compare them to