Well, fountain pens are actually worse for lefties because the "push" motion tends to tear the paper. If only there were truly functional, smudge-free inks! While some brands claim to be "smudge-free," they don’t dry quickly enough to prevent smudging from a lefty’s own hand—they seem more focused on preventing smudges from other objects rather than the writer's hand.
As for pencils, they’re not much better than pens in this regard. The smudging issue persists, just in a different form.
You might recheck your assumptions. It’s possible you’re pushing too hard (since it’s not a roller ball, you don’t need force to get flow). And there’s a variety of different “grips” for us lefties, and I write daily with my vanishing point and kon peki ink with no smudge.
I’ll agree somewhat on pencils, though. I used to have gray hands when I was in high school after all my notes.
As for pencils, they’re not much better than pens in this regard. The smudging issue persists, just in a different form.