I would presume you are right...the more the merrier.
They are looking for bugs which means the more people doing stuff, the more flaws that are uncovered.
That is an excellent idea, putting a banner at the top telling everyone to try it.
Sadly, some developers, while great at code, simply do not think as you do...they get so focused upon the tree they miss the forest. Of course, this might be why they are great developers....they can stare at code for hours.
Me, I am so adhd, I am bouncing around from page to page all the time.