I do this stuff by hand. Not with a simulated camera. And I think that foundation is what's at conflict here with your understanding.

And from there comes your limited, more specific use of orthographic projections. Despite the fact that plenty of CAD software includes isometric orthographic projections in their views, like Autodesk and AutoCAD.

The software is correct that it's orthographic since your camera exists independently of your model space, (unlike modeling programs like SketchUp which aren't typically for rendering) you can set up your camera along perpendicular lines.

Now you're getting it!

Remember. Orthagonal means 90° angle.

Right! With respect to a projection plane. I refer you again:

However, orthographic and orthogonal more correctly refer to the right angle formed between the projection rays and the projection plane,

I don't know what's so hard about saying "I understand now that isometric, multiview, axonometric and more are all orthographic projections mathematically. I was wrong to assume that the projection plane does not have to be fixed along a principal x/y/z axis, though it is easy to see where the confusion comes from in the nature of my trade." Good lord.