The site originally operated that way. It was a place to see listings available and then you'd message the seller to buy the item. I liked it that way. I knew my listings were on the site even though I didn't personally put them there. Once I knew they were there, I did use their features to mark items as active or sold which was nice.
I think its a natural evolution for a marketplace site to want to facilitate the transaction process between the buyer and seller by implementing a buy now button. This feature was added at some point but it did not require intervention or authorization on my part. I think it can be done for both digital and physical products but there needs to be a layer of security to ensure the money goes to the seller.
I believe there is a bright future for commerce using nostr and Bitcoin. There will be bad actors who will take advantage and exploit the open nature of the protocol and the naivete of its users. We have to understand that and operate accordingly.