I remember tummy time decades back, but I also think the marketing of mats/toys for tummy time on the floor has made it more of a thing as it was. Like a PP said: We were told tummy time can include baby lying / sleeping on your chest. I expect most parents will do this sort of thing without labelling as such.
All my kids for the first few months spent a lot of time laying on my or their father's chest - they'd lift their heads for a bit and look around before they'd clonk them back down. The idea that it should be on the floor with these devices to make it better is what is nonsense. Even my child who became very kicky do not touch' around 6-7 month was happy with this during the time when tummy time is recommended. I don't recall putting them on the floor for it.
I've no idea on colostrum harvesting, but I had my kids in a time, place, and around people who openly called breastfeeding disgusting so there was not much about it in discussions in real life, only the online wars I saw from time to time. It was also a time and place where I had more than a few people freak the fuck out about using baby carriers rather than pushchairs, even when I was using a mobility device that wouldn't work with a pushchair - literally had people shout at me in the streets over it.
I was also a bit 🙄 about this one. Who has a big enough house to dedicate an entire bedroom to a mattress, moving everything else out and having nobody else sleep in there etc?
I'm not sure where the idea that floor bed means no one else sleeping in there and nothing else in there came from - it's literally just putting the mattress on the floor or on a very low frame so they can get into and out of bed themselves with minimal risk of harm. This can be done with other furniture or even other beds the small child cannot climb on in the same room.
There's a fair bit of privilege inherent in this - many babies do not have a room to themselves. Most babies under 6 months old are in their parents room.
All of my kids shared a room with their father and I before 10 months, all but one until after a year. Two of them had floor beds when they first moved into a separate room, both because they moved around a lot in their sleep and woke themselves from hitting/kicking the sides, so we wanted bigger beds, but also not ones they could really fall out of and get hurt. My DS1 was also really restless when he was young so he had a double that a parent could lay down on. DD2 was in a single and shared her room with both her older siblings who were in a bunk bed that DD2 couldn't climb until she was closer to 2 and in her own proper bed. We had one of those soft chairs that folds out into a mattress for a parent to lay down on, I think us parents were on floor mattresses far more than the kids.
If you want to think a mattress on the floor is a fair bit of privilege, that's up to you, individual beds at all can seem a privilege compared to many across time and place. It does seems a little odd to me that something I've known more than a few parents have done because a bedframe broke and couldn't afford to fix it or after a scare when a young child has managed to fling themselves out of a cot and it was the only option available has become some sort of wealth symbol, but it's not the oddest thing I've heard where something normal in poverty is made posh.