For me this type of sign up applies to only a handful of very simple flows. For most forms this feels like it would recreate the experience of ordering at a fast food restaurant with a not-so-sharp employee working the register. Unless the order is very simple and common, with few steps, I’d much rather fill out a form and hand it off to be processed.
Think about how long it’d take to complete a simple online checkout with this type of conversational form… What’s your name? What’s your billing address? Is that the same as your shipping address? What’s your ZIP code? What’s your email address? Can you type that again to confirm it? …sounds like a pretty shitty ‘conversation’ if you ask me.