I don't know why so many writers pick this tic up, but it's woefully widespread: using those in place of people.
In most cases, it sounds at least a little stilted (and it can be rather confusing).
Here are some examples taken from the Web:
"U.S. Sen. Lindsey Graham said those who turned over more than 90,000 classified war documents to the WikiLeaks website 'have blood on their hands' and must be found and prosecuted." Why not "people who"?
"Touched by childhood tragedy, Betty Chinn brings hope to those who have fallen on hard times." "People"?
"There are those who launch businesses, and then there are those who do it again and again." Why not "There are people" or "There are entrepreneurs," to be more specific?
I'm OK with the determiner those referring back to an antecedent noun if it has already been mentioned. It's when the noun hasn't been mentioned yet that things run the risk of getting confusing.
I understand that using those this way echoes an archaic way of speaking common in lofty quotations: "Those who cannot remember the past are condemned to repeat it," for instance (thanks, George Santayana).
To my ears, this sounds too mannered for modern writing.