"Reliability" is a different term with "quality". I have a very reliable stone on my floor, but it can't produce any music. The main problem with "discrete opamps" is their physical sizes, which almost inevitably led to excessive inductance and capacitance. The parasitic additions are not only in the power supply circuit, but more important - in the signal path. That is why the practical usage of the parts is very limited. The "extenders" even worsen the problems. (But - hey - this was already explained by JH)
It's a pity, but many companies play the "discrete" card for profit, not for real improvement. This example is one of that sort. Just compare the quality of the Bugle PCB and the opamps PCB. The Bugle PCB is well thought (including the capacitance and inductance minimization, power supply planes, ground plane and so on). I can't say about the opamps the same things. The ground wire, long (inductance) and prone to EMI itself, is something "over-the-top" feature sort to say. And the hand-made design is far from professional look and feel. I don't think that the Hi-End users (to which the company targets the devices) ever touch the thing.