The old methods have been working for the past ~1600 years, why change them now?
I agree on the use of uchiko powder, should be used only when theres a necessity as whiping with clean, lotion free tissues do the trick to remove old oil.
chemicals on your blade would be a nono i think, however some people will tell you that its okay to use "some" to clean your blade, i for one will stick with the old methods as you never know what effect a chemical that wasnt there back then will have on your blade, in the long run after a couple of years of usage.
over oiling is another nono, soaking the blade in oil will make the scabbard moist and that will promote rust, quite the opposite of the initial wanted effect!
self fixes on the blade is yet another nono
In short... its the usual stuff you read everywhere!