Well the only situation I could see frogs being on paper towels is for a quarantine process i.e., make sure the frog doesn't have any illness' and exposes it to the rest of the frogs and or reinfects their self. Paper towels don't hold moisture as well as coconut fiber and will make you have to spray down continously throughout the day. Replacing daily could leave your frog with stress if you're constantly switching out his bedding and handling him or her during the process.

Purpose: Instinctual - their built with strong hind legs, rest, aestivate (hibernation), thermoregulate.

The only advantages I could see using paper towels is easy to clean and easy to keep track of food that you are putting in their. Other than that it's not really recommended (stress-related).