But I'd like to highlight other forces. One was technological, 3 TV channels or whatever was all they could do, and this implied that there was going to be a pretty high degree of conformity. You couldn't broadcast weird Italian movies because only a few percent were interested. The 4 big car companies who bought the ads which paid the bills really didn't want to be associated with anything partisan, they all needed to sell to everyone.
Another was historical / emotional. The nation had just emerged from this gigantic world war, and it was a spectacular victory, which gave enormous prestige to the huge centralized machines built to fight it. They built a lot of similar machines back home, big corporations with a commander-in-chief who wasn't a self-made robber barron, he was promoted up the ranks. Big unions, and big regulation.
This experience also squashed a lot of earlier differences. You say "Women? Marginalised people?" but this seems like a modern take, I think they would have said "Irish? Polish? Jewish?". These earlier identities and divisions were eroding in favor of this shared one, I mean, a Catholic could be elected president, that was a big deal.
But all of these are gone now. So perhaps 100 years ago is a better guide than 50 years ago.