It's a good point. If there's nothing to hide, then it's best to use existent marketplaces on the clearnet.
I seem to recall quite a bit of legitimate business was taking place on Silk Road which I guess makes some sense there was illegitimate profit ready to be spent. Unfortunately that didn't stop the legit money being stolen by the US government. And if it ain't law enforcement then it'll be the site operators themselves.
I can see now how you're thinking. I don't think many others feel the same.