- there aren't great ways for people to offer multiple items apart from making one listing with all the stuff (And having to update all the time)
- You have to do the whole "negotiate payment mechansim and shipping" thing every time. They could easily provide a sort of flow for when an agreement has happened
- On the buyer side you gotta basically just go in and delete your listing when it's done
There's an alternate universe in craigslist where you could somehow signal "I have a potential buyer" to put the thing in hold, and a single-button finalisation step when its done. Similarly, sellers could be able to register certain info to just plop it into a message.
I understand that the existing UX (mainly e-mail forwarding) makes this hard. But... well maybe they can change their UX
These are valid issues but I think they aren't a big deal. Every other platform I've seen that tries to be "smart" and offer these features ends up overdoing it and making it way too complicated & time consuming to post an ad for the first time.
CL in contrast is easy & understandable. You post an ad, post a price, and done. No "profile" or "account" to manage, etc.