Kind of forced economically but also culturally.
In the 1950s, fathers worked and paid for everything. Mothers raised the kids. This was taught in schools, girls were steered into marriage, motherhood, and housekeeping and men into vocations or college.
Let's not pretend that many women didn't go to work so they could have more, and feel like they were a more complete person. Many people just don't want to be pigeonholed into roles defined by tradition, and the 1960s were a huge rebellion against this. This wasn't some grand capitalist scheme.
It's still possible to raise a family on one professional income, if you live like most people did in the 1960s. Can you do it on minimum wage? No, but you couldn't do it then either.