Although twitter has been getting more and more closed it'll take them a long time before they're as closed as Line. The word that best sums up Line and the company behind them is 'opaque'. My kids both had Line installed on their phones. When we got a Nexus 7 tablet they naturally wanted to do Line there as well. Bad idea. Line doesn't allow the same account on two devices. Line's solution? Instant deletion of the account. They lost a year of accumulated stickers and chats. The positive thing from my point of view is that they were completely discouraged and they no longer waste time on it.