Baby shower RSVP

Ok so this is not just for baby shower but parties in general! Does anyone else find it rude when people don't RSVP and or even worse RSVP and tell you days before they can't make it anymore...I'm dealing with this and have dealt with it before and I find it quite annoying and rude. It's not fair for the person throwing the event to have to try and figure out how much of everything they need if no one says anything or just backs out last minute. Sorry I'm just venting! I guess people don't know how to simply say yes or no to something 😣😣