> I moved, so now I have to go through all my key accounts (banks, credit cards, student loans, etc.) to update my address. Why?
Well, try thinking a bit more deeply. Imagine a system where you only have to visit one site, log in, and change all your personal connections with a few keystrokes -- billing, bank accounts, credit cards, address, personal identity. Very convenient!
Now what happens if someone guesses (or steals) your login and password? They would have total control over your life -- they would in essence become you, but without your wish to live a long, peaceful life without being robbed of everything, even your name.
> Am I missing something?
Yes, you are -- you're missing the wisdom that comes with experience.
Did you know that the U.S. government has three branches? Many people know this, but far fewer know the reason why -- it's to make it more difficult for someone to concentrate too much power in their hands. This is actually the reason, crafted by the founding fathers, to protect against a system where the exercise of power becomes too easy.
It's the same here -- the fact that you have to visit a dozen sites and spend hours making petty editorial changes, protects you against identity thieves.