Which they can still do! And are in a way (they also showed integrations with assistant and APIs at the same time as showing Duplex).
But that assumes that businesses have the time to integrate, that they care to integrate, and that they can repeat the process for every proprietary API and service out there.
That requires a fulltime developer or another service that does the integration for them. Which again isn't a problem for a lot of businesses, they might be more than happy to do that, but we won't ever hit 100% coverage with those services, especially not across all the "smart assistants" out there.
This allows users to work with almost 100% of businesses right now, and businesses can further integrate without duplex if needed/wanted and the user will not have to care what system the business uses, or how it integrates.
But that assumes that businesses have the time to integrate, that they care to integrate, and that they can repeat the process for every proprietary API and service out there.
Google is the 800 pound gorilla. Companies would integrate with them if they don't want to be left out.
This allows users to work with almost 100% of businesses right now,
You're assuming that it will be good enough and that the businesses won't hang up on it like people do with every other spam automated system.
They already do this actually, but the coverage is pretty spotty. There are still restaurants that don't have websites and you're asking them to set up a digital booking system through Google. It's just not going to happen. Also, I see this tech as more of a way of training up their AIs on tasks that provide a bit of value while they wait for people to connect to the official booking APIs and such.
And this runs head long into competitive issues. Google says they'll integrate the Google Assistant with OpenTable to let you book tables, but what's the chance OpenTable would nix that integration if Google was trying to make a free competitor? Google doesn't want to be in the restaurant booking system business, and this let's them offer a service in their assistant that no one else can.
Companies already go out of their way to place nice with Google (AMP pages). OpenTable really wouldn't have a choice. By being the default, Google has a competitive advantage.
Google doesn't want to be in the restaurant booking system business
Google wants to be in every business where they can gather data to better target advertising.
I'm sure companies would jump at the opportunity. Google gets more information about people's habits and it the success rate would be a lot higher.
"Don't let overly complicated be the enemy of the simple"....