People did not understand

That's actually my point: they passed major legislation based on a guess not supported by knowledge. People knew THAT is a bad idea in the 1920s (and 1919 when the law was passed), though it seems to have been forgotten in the century since..

Also, many people, mostly men, did not think there was a domestic violence problem because they thought it was an okay thing to do

I'm fully aware of that. My point is that the people who didn't agree that it was ok was wrong to pass law based on an unproven assumption as to the underlying reasons.

You are looking back on it with 2024 knowledge and values.

More like 1990s values at the latest. Demagoguery and scapegoat politics haven't gotten the bad rap it deserves in the wider population for a LONG time..