I use the Lansky System to sharpen my pocket and hunting knives. I get an edge that will shave arm hair, especially my Gerber knife. If I put the knife away for a few days, it will not be as sharp.
Steel begins to oxidize immediately after it's sharpened, microscopic, but there, none the less.
I think by stropping we are removing that layer of oxidation that has formed on the edge since it was last used.
Tom