I don't know, I just feel like it's BTC, PGP, and encrypted computers that keep people protected. I also heard of a clearnet site that's legitimately selling weed. I'm sure if feds want they simply order from a vendor, find the return address, order again and stake out the location. In theory I think a clearnet market is definitely possible.
Or maybe I'm just dumb.
Tor is easy to use. Why make it simple for the Feds to track which markets you are transacting with? Without Tor, even if you use encryption, they will get the meta-data on who you are contacting..