People are playing games online that are free. Unfortunately, without a good business model, free online gaming websites will usually shut down because of lack of money. Therefore, the online gaming owners need to find a way to get their players to pay either directly or indirectly.
Advertising is the main revenue stream for most websites. This seems to be changing.
Super Rewards seems to have found a business model that works. World of Warcraft, Runescape, and countless others have used other business models that seem to work also.
Therefore, letting players play for free does not mean that the online game(s) will not make money. It means that the owner will have to find other ways to coax the user to pay small amounts of cash.
My kids, like many others, buy cards from the store to get rewards for various online games. As an adult, I am quite surprised. I assumed that the free revolution is going to be the future. I am wrong.