Meeting organizers know too well that if you get 40 "yes" RSVPs, you'll get 12 attendees, maybe even less.
When did it become so acceptable to say yes, I'll be there, and then not only fail to show, but to simply ignore the entire thing?
Yes, I'm a crusty old codger who believes that manners matter as a foundation of business. But I'll bet even you young folks would prefer to get 13 yeses and 27 maybes than have those 27 people say something they don't really mean.
Don't use your RSVP as a way to reward the meeting organizer for having a good idea. Don't use it to fill up your calendar so you look busy (nobody cares if you're busy; they're too busy to notice.) Don't tell them what you hope to do, tell them what you intend to do.
Hold yourself accountable for keeping your word in even the little things. It's the only way to be absolutely sure you'll be keeping your word when the big things come along.
Besides, your prospects might be watching, and you know you want them to think you keep your word, right?