This isnt true at all, UA was far more burstier than rapture is and UA had very short durations you were losing a few seconds at worse but gaining a shard back from drain soul AND any UAs that didnt get used up were refunded.
Rapture at a baseline requires targets to have DoTs on them to do dmg. in order for it to do comparable dmg to UA dumping then channeling than it would at a baseline require to have all those DoTs on the target. where as UA speder was just a hard hitting ability on its own.
I am just going to repeat myself here since you are clearly not reading(or can’t read, one of the two).
hopefully you actually read this second time around.