For me, and most people I've worked with, having an all-day meeting specifically to mimic the open office is not something we'd ever propose ourselves. Was it a bottom-up or a top-down decision? Is everyone happy with it?
The meeting grew organically: When I started in Corona times I had a few meetings a day with my mentor to talk about open points and questions. From there it evolved to a permanent meeting, also with others joining.
Attending the meeting is not mandatory; everybody is free to join and leave whenever they want. Some use it more regularly, some don't. I haven't heard of anybody not being happy with it.