The best analogy is still E-mail. [email protected] can talk to [email protected], which can talk to [email protected]. Sometimes an email service shuts down - has anyone checked if yahoo still exists?

So in that case, you have to get a new mail and probably move your important stuff over. It sure sucks, but there is no good way around it, if you want to be able to choose between different services.

Imagine everyone using only gmail: what if Google decided you smell and they don’t want your business any more? What if Google decided to make every login cost $5? Or that you need to say “I love Coca Cola” to read your mail?