And yes, nighttime is different. During the day there are no restrictions on movement around and in and out of the ward, it is expected that people will be having discussions, doctors are doing their rounds.
At night, lights are dimmed, there are rules about not leaving and re entering the ward, people are expected to speak in hushed tones, doctors are not doing their rounds, it's basic obs and urgent interactions only, even those who are being bought onto the ward having just given birth are bought in as quietly as possible.
This is all to support the goal of encouraging the women to sleep. Being asleep around strangers is automatically a vulnerable experience for many people, that sense of vulnerability is heightened for many women when the strangers are male. Anyone who can't imagine why that may be is either being deliberately obtuse or has lived such an innocent and sheltered existence it's hard to believe.
For all the "my partner was there for me and the baby 100% and never would have intimidated anyone". There is no way any person is 100% engaged in taking care of their partner and baby 100% of the time. There will have been periods of time where you and baby were both asleep and your partner was bored. What that may look like to someone who doesn't know them, is a male stranger staring at them. Now he might have just been staring into space, he might have been asleep with his eyes open, he might have been staring at them. There's no way the exhausted, scared, in pain woman would know which of those is true, she just knows how she feels.