The Dreamsurges vendor area has unrestricted mount access and so players are intentionally standing on the vendors blocking NPCs. Fortunately, there’s an easy workaround to interact with overcrowded vendors!
If you can’t interact with the vendors on live servers, you can bind the Interact with Target function in Key Bindings.
All you have to do is open the Game Menu and select Key Bindings. Scroll through the list and under Targeting Functions select Interact with Target. If it is unbound, select a key you want to bind it to. Save your keybindings.
Now, go to the overcrowded area. Type: /target NPC Name into the chat and click the Interact Key you bound in the previous step. Fo instance, I’d like to interact with Archdruid Hamuul Runetotem, so my macro that needs to be pasted into the chat will be: /target Archdruid Hamuul Runetotem.