We have a friend who, when we invited him for parties, he'd come at the end time. So if the soiree was from 2-6, he'd show up at six. And want to hang out and have a beer.
Notice how I said "invited"? We don't invite him anymore. We realized he wanted the one-on-one with us, so now we invite him to do those one-on-one things at other times.
I don't think I'm offended by people arriving late, really. It's more that, now we have Kiddo, I don't really want people hanging out while we are getting him ready for bed and move on with our evening. We just kind of shoo stragglers out, tell the late-comer "Thanks for stopping by. We'd love to talk with you more another time. Call us when you want to get together!" and leave it at that.
And I'd never take a reality show as the norm (not that you were, but reality shows are often so unrealistic as to be absurd.;) ). I can't imagine a gathering at our house where our guests would behave that way toward each other. If it happened, I'd hardly invite them back. How rude.