Because samples are pointless, and a waste of space, so they are half-assed or simply old posts that are linked for reference. Abolish samples when?
Disclaimer: The opinions expressed here are purely personal and do not represent the viewpoints and beliefs of the roleplaying community as a whole.
I don't disagree with their necessarily being useless – I ran a game before where I just asked people to link to old posts so as to ascertain that they could actually write. So I'm sympathetic to that argument.
But yeah, like I said, if actually take the time to use it to write your first post, I think it can have some use. Though arguably your first post might not always be the most representative of what you'd like to do.