Earlier quoted context omitted.
But that is how we used to buy a plane ticket. Long before flights.google.com's price table, you'd call a human up and tell them you'd like to go on holiday. They'd ask you where and when and how much you could afford, and then after a while with the old system (SABRE) clicking and clacking they'd find you a good deal. After a few flights with that travel agent, they'd hey to know you and wouldn't have to ask so many…
I don't see how "but that's the way we used to do things" is an argument in favor of conversational interfaces. The whole point is that we currently have better , more efficient ways of doing those things, so why would we regress to inferior methods?
To relate to the article - google flights is the Keyboard and Mouse - covering 80% of cases very quickly. Conversational is better for when you're juggling more contextual info than what can be represented in a price/departure time/flight duration table. For example, "i'm bringing a small child with me and have an appointment the day before and I really hate the rain".
Rushed comment because I'm working, but I hope you get the gist.
Current flight planning UX is overfit on the 80% and will never cater to the 20% because cost/benefit of the development work isn't good