Computation BURNS energy, it IS a physical process, it's NOT etherial spirit

From David Wolpert, Why Do Computers Use So Much Energy?, Scientific American (4 oct 2018)

Precise estimates vary, but currently about 5 percent of all energy consumption in the U.S. goes just to running computers—a huge cost to the economy as whole. Moreover, all that energy used by those computers ultimately gets converted into heat. This results in a second cost: that of keeping the computers from melting.

The brain, too:

This particular computer uses some 10–20 percent of all the calories that a human consumes. Think about it: our ancestors on the African savanna had to find 20 percent more food every single day, just to keep that ungrateful blob of pink jelly imperiously perched on their shoulders from having a hissy fit. That need for 20 percent more food is a massive penalty to the reproductive fitness of our ancestors. Is that penalty why intelligence is so rare in the evolutionary record?

And then we have the various cellular systems that can be considered to be computers:

For example, a large fraction of the energy budget of a cell goes to translating RNA into sequences of amino acids (i.e., proteins), in the cell’s ribosome. But the thermodynamic efficiency of this computation—the amount of energy required by a ribosome per elementary operation—is many orders of magnitude superior to the thermodynamic efficiency of our current artificial computers.

Tradeoffs:

Conventional computer science is about all about trade-offs between the memory resources and number of timesteps needed to perform a given computation. In light of the foregoing, it seems that there might be far more thermodynamic trade-offs in performing a computation than had been appreciated in conventional computer science, involving thermodynamic costs in addition to the costs of memory resources and number of timesteps. Such trade-offs would apply in both artificial and biological computers.

There you have it, the physicality of computing involves time, storage, and energy.

“...computers...are often very-far-from-equilibrium systems.”

But the article says nothing to answer the question posed in the title: Why? More likely than not, the title was written by an editor, not Wolpert himself.