I will say it depends i used to QT all my fish, but always had some deaths that where out of my control ( lost a flame wrasse that caught popeye because he hit a piefe of pvc pipe too hard, had another wrasse that jumped through a tiny hole where the pump wire went through. Now i only buy exclusively from tsmaquatics.
If tsmaquatics qt's then they probably have the same issues, but better qt tanks and less issues. I like the hobby aspect of qt'ing though, so i do it myself.