Stainless has come a long way in a very short period. I'm old enough to remember the high premiums and long waiting lists for stainless handguns. Also, warnings that people should stick to carbon steeled guns. But then, I recall the derision of "Made in Japan" labels!
I don't know why knife makers went from 440C to some of the crap they're using now. Okay, okay, I have some 440A knives that I absolutely love, but there's no excuse for using AUS4 and 420J2 unless you're going to use the steel in or around salt water. AUS6 is the absolute line and I'm no huge fan of it; still, I have some blades made with it. Most of those models are now being made of AUS4. Go figure.