The author makes valid points from a customer perspective. But as they say, there are always two sides to a story :)
Since a lot of companies are using KooKoo to provide a telephony experience to their customers, I thought I will list out a couple of reasons why gatekeepers may be good, especially if done correctly.
Disclaimer: This will be a little biased post as we provide services to a lot of these "Gatekeepers" :)
1. Monetization: As Sinha mentions in the comments of the above post, in India, lead monetization is very very hard. Businesses in general do not want to pay up for leads and these numbers provide a provable lead generation model for these businesses. The more money the companies make, the better service they can provide for you.
2. Quality control: The example given in the above article takes an example of a clinic. If we take personal examples, most of the times I call a clinic I end up just getting either a busy tone or no one picks up the call. Same is the case with restaurants. Thanks to new services, I am now able to reach them more reliably and they are able to reach back to me. In fact, these gatekeepers can go one step further and rate the clinics and restaurants on their responsiveness also. That will give a better experience to the end customers.
3. Extra service: Not all businesses have the wherewithal to run a support center. So these gatekeepers provide add on services to these businesses which will help in improving customer experience.
That said, I agree with the above article that customer experience is paramount. The gatekeepers have to be extra careful and think through their interaction mechanisms and make them as much meaningful as possible to the customers. In this case, I think Zomato does a good job as they clearly state that this service(the extension number) is provided by Zomato so that the customer knows that the phone number is not the restaurant's number.