Parallax can be unadjusted as long as you stay behind the center of the scope...... Its only if you nod off to a side that it'll affect you.
As to reasons why to an engineer.... sorry I'm far from that, I only report what shows up on paper in real life and could care less why it shows up.
Much like a chrono telling you this is the lowest ES/SD, and will be your best load ,but the target telling you the load sucks, go with paper...
Jeff
