I'm only aware of open bazaar but with open sea, why it is on number 1 on your article? And the same goes for the origin protocol. I don't know these marketplaces that you are suggesting.
Why not include the forum's marketplace categories? there are a lot of trades that's happening there.
A marketplace is a place where you can exchange crypto for products. Don't think about it as a place you exchange cryptos as that is more of an exchange concept.
Opensea - You can purchase ERC-271 tokens (items on the blockchain)
Origin Protocol and Open Bazaar - You can get items for your crypto.
When he mentioned marketplace the thing that came into my mind is exchange. I thought I'm gonna see binance on the list, so meaning marketplace mentioned is where you can purchase tokens or products that accept crypto tokens too.
Is these marketplace are well known to be honest never heard of it aside from Origin Protocol which come to my mind since Ive read of them before.