Saying most fights aren't like UCoB when the point is SMN is at its worst incarnation ever for downtime flexibility is doing a disservice to what Myon was trying to convey.
UCoB and Uwu are most definitely not comfy fights when you have variable nonsensical pushes from party dps variance that can make the fight go from tolerable to having barely anything for the phase. This can be experienced with Nael and trios+, this can be experienced with Primals - but at least there's the Ultima Weapon intermission to act as a grand reset and correct all of the timers for that reopener. We were incredibly fortunate that the first raid tier was fairly light in awkward jumps.
If we want to get particular, every expansion since Heavensward has been several steps backwards in downtime flexibility, from Aetherflow lock and the inability to have Stacks with Aethertrail on the same gauge slot, to rigid 60s Trance Timers and target required 30s Aetherflow stack generators. This is why the 55s Trance change, while a bit of a trap for the inexperienced, is huge just for having a bit of flexibility brought back to the job, just as instant Egi Assaults did with being able to use Ruin IV more flexibly and have more options for mobility. Now we can counteract and adjust for Trance drift whether forced or from downtime instead of only drifting forward.
Can you imagine how awful Polyglot would be if stacks had to literally be used on a target on cooldown the moment they became available or else the timer would freeze in place and forcibly drift? Things like that are not fun for any job.