Yes, the needle moves a large distance, but it does only in response to air flow and to keep the airflow relatively constant. The steady-state position is basically fixed for any given airflow. And it still takes only a tiny movement of the jet to change the mixture.
And I have been through this a time or two, its not just theory.
FWIW, I use plain white toothpaste and my fingers to polish the jets. The shinier they are, the easier the choke will work and the longer the seals will last. The Moss seals are good (although the ones they sold me were not Viton), but in my experience the cork will work fine for a year or so.
Ordinary Buna-N o-rings seem to last well too, mine are going on 10 years now.
And there might be something to be said for cleaning that area every few years anyway, especially if you don't use a paper element fuel filter. Mine had a lot of very fine silt in them, which felt abrasive and is probably dust from the air. (I live near the desert and we sometimes get very fine sand particles in the air).