The debate looks like a retarded one so I haven't followed it but here are a few tidbits for the few posts I've read:
There is no
perspective in parallel projection. You
can't have perspective in parallel projection. That's like saying "I eat lots of meat for my vegan diet". What you mean is projection angle or viewpoint. It's unwise to use the word
perspective here to mean the viewpoint due to the context with exclusive projections methods.
You can change the
angle of projection in parallel projection to see the 3D scene from different viewpoints (ie. from different angles) and you can move the camera around in parallel projection to pan the scene. Just as you can in perspective projection.
Here, a game scene from various angles and zoom levels in parallel projection:
And from various camera positions (look for the same room of boxes with mouse cursor as a reference point):
Same scene with similar angles and zoom levels in perspective projection:
And from various camera positions:
And here's a comparison between parallel and perspective projections as a reminder for why the former is superior for games with this type of viewpoint:
( Vault Dweller you can still redeem that piece of shit camera of yours in AoD. No more height and collision problems since it won't matter how high the camera would be; the scene will remain the same. Also add step-rotation by angles, preferably 45°.)
And depending on your game development goals, 3D isn't pointless at all to use with fixed camera. Depending on your goals and the scope, 3D can often be cheaper, faster, easier and since we're long past the infancy of 3D, usually it also looks better unless you have good 2D digital artists worth their shit. Discarding 3D unconditionally is quite fucking retarded.
As for Project Eternity, they are using Unity as the engine which is a 3D engine and its 2D interpretation is also based on a 3D API. This is one of the silly reasons people have discarded it as a viable option for 2D games which is quite fucking retarded TBH.