PBA, Hashem blessed families with both genders for a very good reason. There is nothing wrong for families to have a Shabbos meal together and I will follow that with it is no one else’s business. It would be up to the individual parents to decide whether or not all their children should join or not. In many cases these families were raised together and the girls are friends and the boys are friends or they are as close as family.
On the other hand, there are many families who invite bochurim from their local yeshiva dorms for Shabbos meals as well. Many Rebbeim invite bochurim home for meals. I have never heard that Rebbeim that ONLY have boys invite bochurim home for shabbos meals or Oneg Shabbos. I have never heard that Rebbeim lock their daughters in the Attic when their bochurim visit either. It is very difficult for families to have so many guests and for Rebbeim to do this if they don’t have daughters at home to help their wives.
I live in a community where Hochnosos Orchim is a huge part of our community. I find this a little over the top.