Hybrid Pen Marks vs Magic Pen Marks
Now, I understand that minions don't have armor, so the arp doesn't help with CSing. And on most Mid Laners and AP champions don't benefit much from Arpen. However I've noticed the amount of penetration both Hybrid Pen, and Magic Pen runes give, and I believe the Value for Hybrid Pen outweighs Magic Pen for 1 reason.
(I'm recalling these numbers from memory, correct me if I'm wrong. I do apologize in advance.) Full Magic Pen Marks = ~7.44 Magic Pen, or less from memory. Full Hybrid Pen Marks = ~5.86 Magic Pen (+the ArPen you get, which helps any champions damage vs other champions due to AA's.)
What I'm asking is; because of the overwhelming Value of Hybrid Pen, why don't we just say 'Screw it' to the 1.6 or so extra Magic Pen from going pure Penetration Marks. The way I see it is that Hybrid Pen marks seem to invalidate Magic Pen Marks.