Please don't read a tone into something that was given in a matter of fact kind of way. That's a mistake that people make when reading messages like these on the Internet. You are free to keep your frogs as you wish.
For what it's worth, reptile carpet is a far better substrate than paper towel for frogs, in my opinion.
The following is not opinion though, it's fact: Aside from the unsanitary nature of paper towel (it is an almost unchecked breeding ground for bacteria and fungus), ordinary paper towel that you buy at the supermarket contains bleaching agents and other chemicals that are not good for an animal with very permeable skin - a frog. In a moist environment, these leach into the water and amphibians touching, standing or sitting in that moisture are then exposed to those chemicals.
So, that is why I said, in my opinion, it is inhumane. I hope this clears things up.
All the best,
-John