This might not be a popular opinion here (so please reply too if you intend to downvote me), and I might be biased because I just came back from F8 Dev Conference yesterday, but I don't think the reason Facebook beats a lot of rivals is network effects, it's because of Zuckerberg. He runs a very tight but organized ship. Let's be real, before facebook and all this stuff, mySpace had incredible amount of network effect and market share for those days, as did friendster (for that era of technology). Twitter had a network effect (albeit, an interest graph not a direct network of friends) and it is not doing well at all, even in areas where interest graph network effects should come in and dominate. You get my idea. I might be biased here because I got a small few minutes to converse with Zuckerberg at F8, but I think calling things simply "the network effect" and being done with it as to why facebook is so successful is a bit disingenuous, it's network effect + right leadership (aka Zuckerberg and to a lesser extent Sheryl). A lot of companies had network effects before facebook and didn't manage their advantage properly. Mark seems to be the overseer of all decisions at facebook and so far almost everything (except for crushing Snap) has worked flawlessly. It remains to be seen what happens with Snapchat.