When you have guests coming round, do you feel comfortable attempting a recipe you've never made before? I'd feel scared to do that as it may go wrong, and when you're already making other components to the meal it makes things more stressful.
YANBU - it's too risky to try a new recipe when guests are coming round and you want to impress
YABU - it's fine to use a recipe you haven't tested yet when guests are over