It would not be legal and more of a black market kinda thing. The government would probably scrutinize the shit out of it.
Your vision is good and indeed it might be the future but man bitcoin has a long, long way to go before there can be sites like these. It could be a thing in niche crypto markets where its legal though.
By the way, you can buy gift cards kinda stuff via Bitcoin.
Craigslist exists (and Romania has OLX), and it's not illegal. Why would a BTC marketplace be? OpenBazaar has been out there for a while and I don't reckon having read about someone who's got a problem with it yet. It's a peer-to-peer market, there's nothing illegal in it.