I agree with the spirit of the recommendation, but not the way it is suggested.
FACT: People are distracted to varying degrees while performing normal driving.
There are countless reasons why the driver of a car can be distracted in the normal operation of a vehicle: serious conversation with a passenger, yelling at the unruly spawn in the backseat, fishing around in the glove compartment, windshield is dirty and driving during dusk when the sun is shining directly in your eyes, etc etc.
FACT: Personal electronics are an additional distraction while driving.
If I'm using my phone GPS capability while actively navigating an unfamiliar area downtown in a huge city, any point I take my eyes off the road is an opportunity to be in an accident. Best case scenario: The GPS device is completely hands off. Fortunately, my upgraded smartphone has this. Answering a phone is very distracting. You have to find it or fish it out of your pants pocket, look at the device to unlock it, and press the button to answer it. Then talking on the phone is distracting. Some conversations more than others of course. It would be great if a large percentage of people could judge for themselves when they exceed the threshold of not paying attention to the road, but unfortunately, most people are incapable of this judgement call.
Personally, I never answer the phone while driving. If it is important, they'll leave a message and I'll call back later. That's not to suggest everybody should be that way, but I do think a hands off system for answering a call in a car would be best. Instead of a luxury item in a car, I think every car made should have a hands off system the easily integrates with the car sound system. A technical nightmare right now, but with a few mandates to the right companies, it could be a reality in as little as 5 years.
What I literally hate seeing is people who talk on the phone nearly non stop while driving the car. Nearly every one of these people are accidents waiting to happen. I am sorry, but you cannot concentrate on driving while always talking on a phone. If you have to make a phone call or answer it, make it short and sweet. You'll live longer and you can talk longer when you are not driving. Driving is not an afterthought - no matter how long you have been doing it. It requires varying degrees of concentration. Most of the time driving is boring, but you need the mental capacity to respond quickly to bad conditions.
In a my perfect world, talking on the phone while driving would be punishable the same way as driving while under the influence. Ergo, the cop sees you talking on the phone, they get an opportunity to pull you over / ticket you and you get to explain your case to the judge or pay the fine. Repeated infractions get stiffer and stiffer fines until at some point you get your license taken away from you.
For those that absolutely have to talk while driving, get a hands off system for your vehicle.