Harlan is one of my favorite writers. And of course on principle I agree.
But few can take this advice seriously.
Face it--writers, even good ones are a dime a dozen. It is a buyer's market, unless you are named JK Rowling or Zane or Dan Brown or Stephen King or somebody else whose name appears on the cover ABOVE the title.
(Ever notice that? )
If you treat writing as a business you understand the necessity sometimes of cutting your price, undercharging and giving away freebies.
Dope dealers are probably among the most mercenary, blood thirsty merchants on earth. Even they put out free samples (sometimes called "testers") so as to get the consumers to come to them.
Writing is a business, and in America, the Land of the Heartless and Home of the Paid, we are in competition.
And so it goes.