> It still had the effect of nearly doubling the size of the workforce

No, it didn't.

That ship had already sailed before ERA was proposed, and was a major driver for it.

It is interesting to think about the societal changes that drive or are driven by a constitutional amendment. If the ERA was a 1920s progressivist goal [1] then maybe one could say that it was part of a broader change to formalize work effort that existed in informal household economies. If the ERA reference is to the early 1970s effort [1] then it was a lagging indicator since the economic integration of women into the formal economy was well underway and would arrive at an equilibrium by the 1990s [0].

Exploring the counterfactual numbers: If the workforce gender share remained at the 4:6 F:M ratio of 1972, then a male workforce of 85m would mean a female workforce of 34m instead of the actual 75m. This would lead to a total workforce of 119m instead of 160m, a decrease of 41m or 25%.

Would the USSR have won the cold war if the US had 25% less economic growth over the last 50 years?

0. https://www.dol.gov/agencies/wb/data/lfp/civilianlfbysex

1. https://en.wikipedia.org/wiki/Equal_Rights_Amendment