Dog Based Gremlin
Veteran
OP got R&B nikkas on his mind 

OP I ain't sayin' you a liar or nothing...but I own Tyrese's first album, so I walked over to my media case and pulled out
the liner notes and it says:
"Lead Vocals by Tyrese
Background Vocals performed by Tyrese and Troy Taylor
All Instruments and Rhythm Arrangements by Troy Taylor
Vocal Arrangements by Troy Taylor and Johnta Austin"
...so...I don't believe you yet.
EDIT - I continued reading and got to the "thank you's",
and he says "THANKS TO EVERYONE WHO COLLABORATED WITH ME"
...and goes to name everyone credited, to which he does not name Usher.
He also continues to thank many others - from executives to people like SWV, Treach, Shaq, and the place he got his tattoos...but not Usher, though.
At the end he says "CAN'T THINK OF NO ONE ELSE".
So...naw, I still don't believe you yet.
Yep you can hear jagged edge on the nice and slow hook.This was a common thing in r&b
Only a few r&b singers did their own background vocals(multi-tracking)