Tanks still can make some things easier for melee players - positionals are still in the game and melees love a reliable tank: Keep the boss facing east after it ignites the forest.
You can immediately have the boss face north after the add phase rather than awkwardly maneuvering it back to mid, then taking mt spot again so that it faces north again only for it to *again* change direction for the next mechanic.
I don't know whether it's possible to invuln an ordeal or immolation to prevent the boss from turning around immediately after.
Also some ordeals configurations allow only a relatively tiny space to both keep uptime and not geht hit at the same time. Many melee players have lost uptime by being bound slightly outside of max melee range while fiddling with the distance. There are still some things to optimize in the fight.
However all of them are rather lame. But so is trying to not lose uptime on Sophia after putting down quasar proximity aoes.
Sophia is a much better fight than Rubicante for other reasons imo: She introduces all of her mechanics early into the fight and then remixes them, rather than backloading the actually fun mechanics as hard as Rubicante or for that matter Zurvan. You are kept on your toes and if you slide off or get knocked back or lazered by the daughter or miss a yin yang, it's because you fd up. Not because you didnt know the mechanic.
Progging Rubi means repeating phases over and over that teach you nothing about the mechanics your party is actually stuck on, turning them into mere busywork and the more complex mechanics aren't fleshed out much designwise in turn.
Immolation and limit cut are the most fun mechanics in Rubi Ex, more interesting than the ordeals, harder to learn, yet each occur only twice/once in the fight and have little variation. I think they got hung up hard on the ordeals and missed the potential in developing those other mechs further.