I believe it is their simplicity that makes social networks like Twitter and Instagram sticky. If a service is easy to use, people are more likely to use it. The more complex it is, the less likely people are to use it.
Absolutely—but there’s something else that’s usually required, too, and that’s an immediate benefit. Instagram is fun to take photos with, and so it’s fun to use even before you connect to other people using it and get hooked. Because it’s immediately useful, it keeps people around long enough to get hooked by following and interacting with their friends.
Twitter, interestingly, is deficient in this regard. Twitter is difficult to grok for new users, and there’s no real initial benefit in sending 140 character messages to the ether. Twitter depends on having people that are interesting and relevant to follow to be useful, and so in many cases it never sticks with new users, because they can’t understand what’s convincing about Twitter if they don’t know anyone who’s worth following.
Yet Twitter still succeeded. I think Twitter overcame this because it had a core base of initial geeky users who really enjoyed using it and understood its value immediately. That base, who didn’t suffer the same problem as regular users, drove it while new users took a while to finally get it and build up their users.
What this suggests is that you can overcome limitations by being immediately useful or by building a strong core of loyal users that can get your network over the regular user hump.