If you're ever interested in taking a more removed perspective view of that particular magazine, take a look at their old articles. 1850s-60s (e.g., slavery). Late 1800s and early 1900s (labor rights). Nazi-related stuff.
It depends if "the value of what they produce" means marginal output or average output. Due to the law of diminishing returns, typically average output is greater than marginal output. The theory predicts that wages = marginal output: if wages are less, you can increase profits by hiring more workers, if they are more, you can increase profits by laying people off. So it comes to an equilibrium where the marginal output matches market wages. Since this is less than average output, it is still possible to make a profit.
I agree though that the article is being misleading here since "the value of what they produce" is an ambiguous term that should probably refer to average output rather than marginal output.
> Nazi-related stuff
I think today's Economist does not correspond to your caricature.
FWIW, they've endorsed the Democrat candidate in 5 of the last 7 US presidential elections, and I'm confident that soon it'll be 6 out of 8.
They're doing the same things they've always done, just with modern issues. They'll be just as disgusting in hindsight for most people. A critical reading of them now will make it so that one doesn't have to wait.
PS, you heard it there first: buy slave-made sugar.