It looks like you're new here. If you want to get involved, click one of these buttons!
Downloading an MMO costs bandwidth. Many people have to pay bandwidth or the internet company to download things. Many people have a bandwidth cap, especially those in Australia and parts of Europe. Some people, even in the US, have to pay extra for the amount needed to download. And to be able to play a game online, you have to pay the internet company money each month to do so.
Therefore, MMOs aren't actually free, even if they say they are. The MMO itself may be free, but to play it, it isn't. This is also true for digital download games (but you have to pay for those anyway), or games that require an always online connection (which costs a lot of bandwidth, especially for those of us in Australia).
So free is an illusion, as people have to pay money to play an MMO or anything else that requires an internet connection.
My Skyrim, Fallout 4, Starbound and WoW + other game mods at MODDB: