It's called the snowball effect.
Roll a hand size lightly packed snowball downhill and watch it increase size as it gathers more snow.
It's also like Facebook popularity. One tells another, both tell even more, then 4 tell 8, then 8 tell 16,32, 64, 128 then later millions.
Things like this always happened in life. In my younger party days It was bars and taverns. In my local area Tuesday night was "The Station complex" only because they had an average band that night. Word-Of-Mouth and Boom !!!!.....Popular !
Let's analyze World of Warcraft:
Vanilla World of Warcraft, first of fun loving easy going second generation mmorpg's. Friendly and social, it was the "first of it's kind" that truly ran on computers when computers were made like crap.
Some marketing and advertisement but largely Word-Of-Mouth. Thousands turned to millions...Finally something new for people at home to do !.... Kids at school had to play or they were rejected in conversations in the school yard.
When something like this catches on, "it can't do nothing wrong*….It will remain popular until the fad is over !
REMEMBER THIS FOR LATER ON.
Obviously as time went on players chewed through the all the content as players explored every tree and rock, Blizzard had to create expansion's.
-The Burning Crusade
-Wrath of the Lich King
-Mists of Pandaria
-Warlords of Draenor
Well, some ware between Wrath of the Lich King and Cataclysm, World of Warcraft changed its formula drastically. MOST WOULD SAY IT'S UN-RECOGNIZABLE. I don't think anyone can argue...It's not the same game.
FORCED changes !!
Millions rejected it.... Millions accepted it
One thing for sure "it can't do nothing wrong" It will remain popular until the fad is over.
Let's analyze EVERY OTHER mmorpg:
With FORCED changes of World of Warcraft and "it can't do nothing wrong", other developers followed the format that millions rejected.
But, players didn't have to accept.... Why?.... They're NOT World of Warcraft.
Only World of Warcraft "can't do nothing wrong"..... Only now, it's a slow dying Fade.