To me, it’s very simple: I work and my wife works. After some maternity/paternity leave, we both need to get to work again to earn money to provide our kids with food, shelter, a future etc.

To be able to work, we need to sleep. For us to sleep, our kids and the baby needs to sleep.

So we put the baby in his own room on day three. Always had him sleep in his bed in his room. Didn’t let him sleep anywhere else (or when he fell asleep, put him in his bed). When in his room, he was there to sleep, not to play. So in short: sleep = bed = sleep = bed.

He slept on his own through the night after seven weeks, with only two half awake feedings lasting maybe 15 minutes.

Maybe in 1950 the wife was raised to not expect a career and could be up all night taking care of a crying baby, and the man could sleep and then on his own earn a living wage for the family during the day?

Maybe in 10.000 b.C. parents could be up all night taking care of a crying baby and “the village” could then take care of the baby during the day while the parents slept?

Maybe maybe maybe, but in 2021 there is almost no viable alternative apart from making sure your baby sleeps through the night sooner rather than later.