Ratios gonna ratio.
It's not mutually exclusive with enormous relative improvement at the bottom, from where people were to where they are now. China and India have all but ended open defecation and there's running water in places we'd never dream of a generation ago. Diseases are being eradicated saving huge numbers of lives.
Rich got richer contains zero information about how poor people fared - even accounting for relative numbers in your claim.
The point is not that the poor aren't better off. They undoubtedly are.
It's the it's the nature of mercantilist systems to leave only scraps for the people at the bottom. The absolute bare minimum to stave off revolution in good times.
This is merely the nature of the beast.
We're way better off in capitalism than other systems (as you can see); but to assume that we just had better ideas like the article suggests to get there is laughable.
Capitalism was enabled by a superstructure of world power that, we must remember, very nearly didn't make it.
Leaving Omelas &c.