How do you know that Hacker News developers are too smart for their own good?

[jgwynn2901]

When "Unknown or expired link" is considered acceptable UI and the Search bar is on the bottom of the scrollable content.

[paulhauggis]

Nobody ever said hackers were UI geniuses. Also,you have to know your community. For this community, the things you mention works.

[a_a_r_o_n]

I can see how the search field works, despite being at the bottom, because "it works."

How does expired links "works?" What do they do for a user?