It does increase security, but I do think that Bitcoiners are obsessed with security. It wasn't that long ago that banks ran on a simple double ledger system, where the bank had a ledger and you had a copy in your chequebook. By today's standards, I'd say that's clearly not secure enough. But I'd also say Juan's statement about everyone being able to verify the blockchain on their home computer is going too far - it's limiting the blockchain to the slowest runners in the race. It would be like a video editor developer saying they're going to make sure their software runs on the least powerful device, thereby sacrificing all the benefits of specialisation.

Thanks for your respectful and thought-provoking comments, they're much appreciated.