Not sure how charging a transaction fee makes it a scam. That's what every company that provides a market platform does.

While it's entirely possible that the blockchain serves no functional purpose in this case that couldn't be done equally well with a web server, it's also possible that they've structured the company so that some parts are done automatically, by a smart contract on the blockchain, resulting in the company having less control than it would otherwise have.

Scepticism is a good thing. Making serious allegations based solely on speculation is not.