I am not sure that anyone would argue that going back to muscles and firewood would be good for us. Sure, the exercise would benefit many of us, although some would have an uphill battle, but
this page says the average homeowner uses almost five cords of wood a year. How many trees it takes to make a cord entirely depends on the trees, but I read that, on average, one tree that is thirty-six feet tall might possibly make one cord.
I do not know why it specified homeowners, except that people in apartments very well might have central heating, and I read there were 125,000,000 heads of household in 2016. Does that suggest we would need to chop down 675 million trees each year just for heating?
That is not a small number!
That is a large number!