Yes this is indeed a tricky thing to figure out. I think as parents we need to really examine the pros and cons of this activity? Paramount of course is will there be the required supervision before even contemplating it.
The pros are that kids can have a blast, become sleep deprived and remember what a great time they had for a long time. I’m not convinced that much ‘bonding goes on” but it sure can be fun, speaking of the experiences my own five kids had.
The cons of course can be fuelled by our own fears and negative experiences. We always knew the families where our children were staying, a categorical must. If there are cultural reasons for not sleeping over then these need to be explained fully to the child ALWAYS acknowledging their feelings and building on what the CAN do, have their friends come to your house till later but not sleep over.
As a group of parents, it is very important that you work together to dialogue about your comfort level and cone to a compromise that is suitable to all.