the issue is that people would probably not want to pay for an app like WhatsApp, and so the 'free' alternative takes hold, and whoever controls that gets the cost of running the infrastructure in advertisement fees.
If some company could set themselves up as a utility, and the mobile network operators were to pay that company to run the messaging app + infra, then it could be made to operate like a utility and nobodies data would have to be sold.
I could remember initially paying for a Whatsapp subscription a couple of years ago, I was happy to do so as I believed they were providing an essential service.