Ron, I suggest that you try to perform noto without having the mune touch your left hand at all. I'm not sure it's impossible, but it should answer your question pretty quickly.
In MJER, we use the left hand much the way Ellis stated, as a guide to getting the kissaki through the koiguchi & aligning the rest of the blade with the saya. I'm not sure if that's quite the same as simulating wiping of the blade with paper, though....
On a related note, why do almost all koryu have us wrap the koiguchi with our left hand so that the opening can't be seen by an opponent ? The best answer I can come up with is that it shows "mastery" of your blade, but I'm not sure that's pertinent.
Ken Goldstein
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Judo Kodansha/MJER Iaido Kodansha/Jodo Oku-iri
Fencing Master/NRA Instructor
"A positive attitude may not solve all your problems, but it'll annoy enough people to be worth the effort."