They didn’t have ensuite bathrooms and open concept in those days.
In my old house, the only bathroom was adjacent to my room and across from my parents room.
I’m in a completely different part of the country, but my house built in 1982 has an ensuite. no stairs, tho (thank goodness). So did my parents come to think of it and they bought maybe 10 years before 82? somewhere around there. Maybe Calif pioneered them first, tho? I am architecturally illiterate.
Every house I lived in from the 60s to today had a master bathroom. Some were originally built years before that. There have been ensuites for decades. I lived in a 1920 or 30s built house that had a bathroom attached to both it’s bedrooms. Our current 1950s built house has an attached master bath.
I was raised in a 2 story house.
4 bedrooms on the 2nd floor—and that bathroom was all the way at the end of the hallway, furthest from Parents bedroom. Bathroom on west end of hallway. 4 bedrooms on both sides of hallway, working east.