Oxygen does leak out a bit faster; some say about 30% faster, but the effect is only 30% of 21%, so not very important. After a few months the remaining gas will be oxygen depleted, so will be very much the same as a nitrogen fill. There might be something in the "dry nitrogen" argument, but I've never seen any condensate/corrosion in my steel wheels; nor do I find any condensate in the air lines that I use to fill the tyres.
Possibly it all started when racers found it easier to fill from cylinders of compressed dry nitrogen, rather than depend on small compressors etc. I'd be inclined to use Argon if it were available.