You know, I can understand where this is coming from, even thought it's very bad advice. It's about trying to make someone feel "involved" even if they can't come to your wedding. It's part of the "it's rude to tell anyone 'no'!" mentality. She's hoping that the people so treated will feel like guests in everything except actually being there on the day.
It's totally ineffective, of course, and very rude. But I can, alas, see people thinking that this would actually placate someone by sending the message "I can't invite you. But see! I still want to spend time with you doing weddingy things! It's not my fault!"