Because they can ask me what the project is about on Skype. Then my partner and I can both explain it and visually show them. Its not like we are trying to hide what we are doing or anything.
I imagine anyone worth bringing on is busy working on their own stuff. It's in your best interest to explain your project. Most people will see your post and not contact you. They won't contact you, and you won't get the opportunity to show or say anything.
I think your prediction was wrong. I had plenty of people contact me. Definitely some that are worth bringing on and are excited to work on the project.