No, it's not the playtesters that's the problem. It's his vision. In the end his verdict was "we did well in the time and budget we were allotted".
While I don't have huge disagreements about his system (micromanagement hell and Empower, Pen, class resources and removal of per rest in the sequel notwithstanding), what the competent playtester should've told him is that the UI, tedious micromanagement of abilities and speed of the combat aren't what a normal human being needs to play comfortably. It is absolutely a system designed on paper without practical consideration. And it plays like designed by aliens as a result. We all know nobody at Obs can play the game on PotD and only 2 people can play on hard. If that doesn't raise red flags internally, that is one dysfunctional company, but we also know that's the case, don't we.
I for one like the gameplay of PoE. Don't think much about Empower and was kinda sad to see vancian casting and health/endurance go, but don't have a huge issue with that.
Armor/Pen is not great, but still better then the DnD abstractions for me. In general the system makes much more sense for a computer game then DnD and plays a lot better.
Speed is rather fast... but there is pause for a reason.
Also I have no problems with the UI. I mean, I was annoyed I couldn't see the ability tree apart from character creation and level ups, but guess what? It was fixed. Also the enchantment menu was terrible... well, it's fixed also (well, almost).