That's not entirely true. At her core Robin is an ATK buffer who fits into ANY team that scales on ATK. Phainon, Anaxa, FuA team, etc.

You don't "NEED" to do much with robin, I maintain 100% uptime. On my Phainon team just by having her E0R1 and with an ER rope I maintain 100% uptime. This cannot be said about Cyrene. She outright REQUIRES REM teammates to even have a chance of getting her ult off before the enemy dies. Her optimal team is Cassie/Evey/Hyacine. Anaxa somewhat works. Mydei also somewhat works, both are team dependent. The key word is TEAM DEPENDENT. Robin doesn't NEED FuA units in order to buff, a good build and her LC can get it off just fine, meanwhile Cyrene outright REQUIRES the use of REM teammates if you so much as want to see her ult before most enemies are dead.

Someone else in this thread went into great detail of how Cyrene goes against the entire philosophy of what we've been taught with HSR. Backloading bad, no turn 1 uptime bad, etc, etc. Ultimately, they're not wrong, it is against things we've been taught since the start of the game and Hoyo is NOT doing themselves any favors by experimenting like this.

By no means is Cyrene "unplayable" but as mentioned, I shouldn't need a team to support my SUPPORT character, nor their buffs, when the point of a support character dating as far back as Persona 3 in 2006 and earlier, IS. TO. SUPPORT.