They were sitting in the slingshot right when people realized that Myspace was terrible. They rode that momentum until they reached a critical mass. Are you going to join a social networking service if only a fraction of your friends or colleagues were members?
IE 6 was really, really popular for a while. Even today, with Firefox, Chrome, and Safari, it refuses to die. It is–and always was–terrible. Bud Light is a terrible beer. Two and a Half Men isn't a funny show. Facebook is a terrible service.
- They can't do privacy right. Period.
- They can't give users features they want. (Dislike button?)
- They force users to use features they don't want. (Redesigns anyone?)
- They can't even get something as simple as chat right.