DJL,
As I noted above, the powder wasn't corrosive, it was errosive. The high flame temperature and the soft steels available in the 1890s led Winchester to discover the same thing that the British did with their cordite of the same time -- either tame the flame temperature by reformulating the powder, take other measures, or expect bad barrel life.
But, given that primers of the time were still corrosive due to the potassium salts, it's also possible that people bought into the old advertising, that the new smokeless powders didn't harm your gun like black powder, a little too much and slacked off on their cleaning regimes, which certainly would not have helped the situation at all.