They shouldn't be so successful. They made the same mistake as Goldman. In this case, small, problematic privacy features (people being able to tag you without

They shouldn't be so successful. They made the same mistake as Goldman. In this case, small, problematic privacy features (people being able to tag you without your permission, etc.) that weren't exhausted + ambitious new platforms and exponential success suddenly caused them to reach a critical mass where people think twice about their service. It's all about the integrity of the core feature set, and avoiding future, short-term successes that erode into it. Ironically, one only really notices the erosions (which, as with Apple and Goldman, are really not unique within their industry) after a certain amount of success.