It was done with both... but limit states for the last 40 or 50 years that I'm aware of... the first CISC steel handbook ('65 edition, I think) that I had had plastic design flexural coefficients tabulated... and working stress design was common at the time... I've been using plastic design for about 50 years, but always with limit states design... we were the first class at UofM engineering to exclusively do limit states design for both steel and concrete... we touched on working stress design, but for historic reasons only.
Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?
