Remember these services are not designed to fulfill a previously existing need. They are designed to become addictive and create a new need, which they then hav

Remember these services are not designed to fulfill a previously existing need. They are designed to become addictive and create a new need, which they then have a monopoly on fulfilling. The applications you are thinking of served preexisting needs, so it required more upfront complexity. Something like Snapchat's UI does not have the burden of fulfilling a previously existing need. That is, until they redesigned it. Then suddenly, the new UI had to provide for a pre-existing need and as an obvious consequence, has been more difficult for both new and existing users.