They said they weren’t going to do their initial idea for trading (the Bazaar) because lots of people didn’t like the idea of trading being a car boot sale (every seller has an individual shop & you have to physically walk between shops, plus they would have given us a random selection of sellers/shops) instead of an AH-interface.
It was always going to be limited as they don’t (& have never) liked the worst excesses of PoE’s trade. Just how limited it was originally intended to be I’m not entirely sure, but the interface (ie, a random selection of individual shops) was going to be far worse than the AH we got.
I’m not sure the Bazaar even got to the point where it could be integrated with the rest of the game since they scrapped it years before MP was done.