To be honest, the first one that comes to mind is HN. There is zero consequence if someone was to get a hold of my credentials here — I don't care about the score and I can still recover the bookmarks.
What if the person that takes over the account posts messages that arouse the interest of authorities? Your IP addresses and other info are associated with the account.
I think this is a pseudo-problem in pretty much any country except for, perhaps, totalitarian regimes or similar. If any large body would take interest in the account seriously enough to get the associated IP, they would also automatically get the new account holder's IP and the clear correlation.
