Onboarding is critical where competition is fierce and opportunities are limited, and where if you miss one chance you're unlikely to have another.
Arguably, the onboarding process for Twitter, Facebook, and other social media platforms is not great, but people are given so many opportunities (and quite often: coercion) to join, that they did so.
Google accomplished this for Google+ by hijacking its extant YouTube and Android registration-flow processes to create new G+ profiles. A platform with ~20m frequent users and perhaps 100--300m who'd ever participated in the platform ... boasted over 3 billion profiles. Because every person who registered a new Android device --- a necessary if not frictionless step in the chain of converting a $50 -- $1,000 brick to something remotely useful --- was captured by the network.
(Many of those devices also had pre-installed, non-removeable Facebook and Twitter apps on them.)
Critical mass, market power, and monopoly abuse also play critical roles here.
Onboarding to Facebook is fantastic. They've invested billions in finding your friends and people you know and inviting you to befriend them on the app right away, solving the cold start problem which Twitter never managed to do.
Arguably, the onboarding process for Twitter, Facebook, and other social media platforms is not great, but people are given so many opportunities (and quite often: coercion) to join, that they did so.
Google accomplished this for Google+ by hijacking its extant YouTube and Android registration-flow processes to create new G+ profiles. A platform with ~20m frequent users and perhaps 100--300m who'd ever participated in the platform ... boasted over 3 billion profiles. Because every person who registered a new Android device --- a necessary if not frictionless step in the chain of converting a $50 -- $1,000 brick to something remotely useful --- was captured by the network.
(Many of those devices also had pre-installed, non-removeable Facebook and Twitter apps on them.)
Critical mass, market power, and monopoly abuse also play critical roles here.