Other than helping to protect e-bays market share 
, the main legit reason that I see for the status quo is that all these Cl search engines are using up resources and bandwidth. I don't know if that's a real issue or a non-issue, but it might play in...
Remember also, that it's not just us who are affected by the difficulty making broader searches, it's anyone trying to sell something unique. There's no national market for used washer and dryers, but anyone with a collectable item wants to be on the big stage, beause at any given time there may only be a handful of potential buyers for your specialty item, and the difference between hitting a rejion versus the country is huge.
This is just a reminder that the internet isn't just our ever-improving toy. There are still gatekeepers and overlords whose whims determine how we play.
