First consider the energy cost of manufacturing paper towels or plastic bags or any other unrecyclable item that we use once and then toss. Some of these items are very useful. For instance, I would not preach against toilet paper.
Then consider the energy cost of transporting stuff to the landfill, and think about the methane and other emissions from those big holes in the ground. And that’s assuming that our trash goes where it should.
These energy costs are unavoidable to a certain extent. But it’s a waste of energy to buy something, use it once, and throw it away if you don’t need it to begin with!