Chat is the interface for when you cannot enumerate the arguments. That is a genuinely important case and it is much rarer inside a product than the number of chat interfaces in products would suggest.
How chat became the default
Chat was the right interface for a general assistant, because a general assistant has an unbounded task space and no way to know in advance what a user wants. That worked, it was copied, and it arrived in hundreds of products where the task space is not unbounded at all — where there are, in fact, six things the feature does.
It is also the cheapest thing to build. A text box and a message list require no decisions about what the feature does, which is exactly why it is so often the wrong choice: it defers the product design onto the user, who has less information than you do about what the system can handle.
What chat costs you
