Damn, as someone who sometimes navigate by guessing URLs and rewriting them manually in the address bar, I hope more don't start doing this, I probably see at least one self-inflicted 404 per day at least.
Faster. Wanna know the pricing? $domain/pricing. What's this company about? $domain/about. Switch to another Google account? Change the 1 to a 2 in the URL. I guess mostly to avoid the mouse ultimately.
Can you scan my bookmarks? :) edit: i.e. if someone has a bookmark to a page on your site and it goes 404, then they are blocked for a year. You have no ability to scan it because it's a file on their local system.