I get that it's useful at time, but come on. Every problem cannot be solved with "I'm afraid that's not possible." At least not in the real world.
People can invite whomever they want to their house. Still, an "I'm afraid that won't be possible" hardly seems sufficient when you want to exclude a sibling or someone's BF, or not invite a relatives kid, or invite one friend and not the other or whatever. It sounds good on paper, but it's just not always realistic. There's always at least one such response when a poster has a problem, and I think it's dismissive and disrespectful to the op. Obviously if "I'm afraid that won't be possible" were a valid option, the OP wouldn't be posting.
Same with "my house, my rules." The OP's are trying to come up with a solution that does not boil down to "it's my house, so you have to do whatever I say, if you don't want to, then just leave." To me that's just childish and selfish.
I'm also quite alarmed at how dismissive people are to their own families. I understand that not everyone is as lucky as I, and some other posters, are in the family dept, but it makes me wonder who the toxic people really are sometimes.